There are going to be several versions of vista 64-bit being one of them. They will be offering a 32bit version as well. I wouldn't run Vista without a decent video card, 1gb of memory and at least a 2ghz (AMD 2000+ equivilent) clock speed.
For the noobs:
Just because your freaking AMD runs at 1.8ghz doesnt mean that you shouldnt use it because its the same power as a 3.0ghz p4...get it?
A+, Network + , HP Certified Tech and MCP
Specs: AMD Phenom II X6 1095T, Asus M477TD, 8GB GSkill Ripjaws DDR3 1600 7-8-7-24 1T, 128GB Crucial M4 SSD, ATi HD4650, W7, 27" HL272 Monitor