I think your best option is too play ME2 on xbox, unless you don't care about your continuity and stuff, sorry dude

yeah saves are not compatible between systems. 
 
However, you're buying it on PC so you could probably find and download a save that will resemble the choices you made in your xbox game and get 99% of the same experience you would. 
 
I think Gamefaqs offers this but i could be wrong, it's been MANY years since i downloaded a save game.

If you want to transfer a save over, your only real option is to buy ME1 for PC, and rush through the main story to make your choices, or play ME 2 on 360. 
 
But at the start of ME2 you get to choose your options anyway, so if you care about continuity in your ME universe, you could always just make a new ME2 character who made the same choices as your ME1 character. You get the option to change most of the appearance & class stuff anyway. The only stuff that completely carries over is the major plot-changing decisions, and you can just select them to be the same ones you chose when you played ME1 .

"If you want to transfer a save over, your only real option is to buy ME1 for PC, and rush through the main story to make your choices, or play ME 2 on 360.   But at the start of ME2 you get to choose your options anyway, so if you care about continuity in your ME universe, you could always just make a new ME2 character who made the same choices as your ME1 character. You get the option to change most of the appearance & class stuff anyway. The only stuff that completely carries over is the major plot-changing decisions, and you can just select them to be the same ones you chose when you played ME1 . "

I preorderd the game fo pc...so i guess i'll go with matty advice, but WonderboyCoz what do you mean "way more than you would think"?