i got a hold of an old dell precision 650. i know this thing is older. but i want to build this thing up anyway. i had some old memory so i put 4 gigs in it. i started installing win7 64bit and get an error saying this is not a 64 bit processor. its a xeon prestonia 2ghz. the main board is model 02K812 with bios ver A05. where can i get info on the best processor for this computer? i know dell's can be hard to upgrade hardware on so i don't want to get something that won't work. old cheap xeon processors are all over e-bay ($10-$20) so i figured getting the best 64bit this thing can handle would be the way to go.