First off, time travel doesn't work in the SW universe, the Force itself prevents it. (The obvious reason is Lucas didn't want anyone to go back and alter the movies' timeline)
Second, SW tech has advanced so much that a bloody TIE fighter can fire off 64,000 GW of particle energy. Turbo lasers even back during the Clone Wars have 200 gigatons of particle energy. They made the Death Star because it's so powerful nothing can shield against it, while planetary shields that have been improving for millennia can deflect them. Plus, the Death Star wasn't invented by the Empire, but by the Confederacy which was made up of Republic corporations. They already had the power to create a superlaser, but what they lacked and what the Death Star provided was an impenetrable shell that protects the superlaser and has enough power for said laser. If you're fighting other cultures who don't have the tech to withstand 200 gigatons of particle energy, then simple cruisers can devastate their planets and you wouldn't need the Death Star. The Empire needed it because the Rebels were well-funded insurgents supported by the Senatorial aristocracy.
Third, SW has all-powerful beings in the form of Light-Sided Jedi who have become one with the Force, who don't interfere in mortal affairs, but then the Q aren't mortals.....so the Jedi who have become one with the force, whom Lucas describes as being far more powerful than anyone can possibly imagine (because they became one with the Light) have no qualms about wiping out the Q if they decide to interfere. Especially since the Q can be defeated by HUMANS during the Q Civil War; one member of the Continuum gave humans weapons to kill off other Q members. At this rate, the Sith need only to persuade one member of the Q that he's better off not listening to the Continuum and using the Sith as his servants, and persuade him to give them Q weapons to wipe out the other Q, then the Sith would turn around and kill their patron Q as well once they're done.
And no, the EU is canon. Lucas talked of parallel dimensions in terms of their development; he even used the EU to tie together the movies, such as Force Unleashed to tie up loose ends between episodes III and IV, and the Clone Ears to explain loose ends between Episodes II and III.
Don't forget Star Wars weapons haven't evolved much (if at all) in more than 4,000 years. Good R&D, dudes.
Star Trek weapons have increased from 5x10^11 joules in Enterprise to around 9x10^13 joules by Nemesis.
P.S. A direct-hit from one of the devastating weapons on Darth Vader's fighter almost killed R2-D2.
"Star Trek is simply outnumbered,outgunned and out-teched.This is all that is needed for their downfall."
Outnumbered yes, but with their lack of FTL sensors and transporters, in what sense do they "out-tech" Star Trek?
Star Wars weapons top-out around 20% of Trek phasers (if you don't count the Death Star, of course)
Didn't an A-Wing destroy the Executor by crashing into its bridge? What good are deflectors that can't deflect low-speed collisions with small objects? Seriously, what are they deflecting?!?
Don't get me wrong, the Empire could probably still beat the Federation and Klingons combined. After all, Trek ships may be three times as powerful and durable, but Star Wars ships have many times more ships and each ship has loads more weapons.
200 gigatons turbo lasers were in use during the Clone Wars as guns for fucking TROOP TRANSPORTS. Proton torpedoes can bypass shields AND home into targets and have just as much a punch as a turbo laser.
At this rate, all they need is the Rebels. Even the Borg would get blown up by the sheer firepower of rebel starfighters, just as they can't defend against species 8472 because the latter uses weapons too strong for the Borg to adapt against.
Plus, I've got a small, portable computer than can conduct just over 2 billion F/E cycles per second and is programmed with enough languages to communicate with 99% of the Earth's population.
It's called a Comm. Badge.
Err, an iPad.
TIE Defenders all the way.........the proton torpedoes can bypass shields, blowing up ship systems quite easily.
Gen. Dodonna: "the shaft is ray-shielded, so you'll have to use proton torpedoes."
But, this does beg the question. Does "The Force" work in all known galaxies or just in that Galaxy Far Far Away?
Likewise, the people in Star Wars are overall pretty peaceful but a war starts up they fight like mad. The people of Star Trek are full of choking peaceful political correctness but ready to be warlike at any excuse. The interesting part is in Star Wars the governments, the officials are most often war like and war starters while in Star Trek the people actually risk getting in big trouble using violence to counter threats because they can't wait for the bureaucracy to give them the OK.
In principle it'd depend on the leaders who'd win. Star Wars led by Vader would, because he's smart enough to work out their tech's potential. They could use droids for shock troops and bombardment star battles in case the phaser/photon torpedo's ability to aim instantly was better than the blaster/shields. Moving far faster alone can win about any war. And not just the Death Star or cheaper "Star Lance", Vader could work out rigging star drives into big asteroids and launching them as cheap bombardments on colonies/starbases. That and pure numbers of troops that could be thrown and acceptance of insane loss rates, Star Wars should win. The pure resource base of Star Wars is easily 1000x Star Trek.
Star Trek led by Captain Kirk just might be able to counter that. He'd work out deals with the Romulans, Klingons for a "Desperate Alliance". The Klingons would be scared, note that the "Empire" was subtly out to marginalize non-humans, but just enough leaked out for the non-human aliens to be freaking out. And plenty of Star Wars aliens (Wookies, Gamorran, Hutt) bigger, meaner, crazier than Klingons. So rather than admit scared, working with their former worst enemy to fight a worse enemy would be not just acceptable, it'd be pure honor. So the klingons would savagely fight to counter the droid onslaught. The Romulans would be jaw-dropped by the "Illogical Waste" of the Star Wars tech and look forward to working with even Kirk and the Klingons to conquer and gain the technology as fast as possible. There is the 1000x resource difference, but Star Wars is heavily leader driven. (at least in the movies) So get rid of Vader somehow and draw lines the Star Wars forces can't get past easily, the next goverment be it Rebel or even later Imperials would make a compromise and cease hostilities and open up trade routes.
Star Wars does have the Force on it's side which is the only equalizer, but stopping a fleet would be a tall order.
Now something like Star Wars vs Babylon 5 would be nasty. Star Wars would have the tech advantage there, but still be close enough (especially with some of the alien B5 races thrown in) to make it a true contest.
Trek shields can't block 400 GW of particle energy, while the max firepower for a starfighter's blaster cannons is 64K GW.