if the desk top wont run AC2 it will never sell because nothing will run it, AC2 does have some graphics enhancements over AC1 but I doubt it will move the min requirements much as they would be pushing past a large part of the market they want to sell to.
Oh, I'm sure either system will run the game. I'm trying to guesstimate whether they will run it enough better than the PS3 that it'll be worth waiting 4-5 months.
In AC1, when I saw online videos taken from console play, I noticed that my laptop was getting about double the people on the streets and was showing more detail at longer distances. Mostly I'm just disappointed that all games run at 720p on the PS3, so I'm looking for FULL HD 1080p on the PC.
Also I prefer my games on PC because, for one thing, I have that nice laptop and can play in airport terminals, and when I travel for the holidays. It doubles as my graphics workstation so I'm already carrying it with me.