EDIT: does some one know for SURE i can de-grade to winxp? because that sale at BB said I cant to do
YES, any computer can run any existing OS you want, from vista, xp, 2000, 98, 95, linux, ubuntu, Mac OS. That guy is just lying to u. If you have the xp disk, you just format the drive and install XP.
I have the same gpu as you, and with 1gb in XP I was running Wow at max resolution smoothly.