It seemed like you were interested in the specifications I gave you earlier. The site I usually rely on is newegg.com. Its easy to search for exactly what part you want. If you want to go intel, I suggest the core 2 duo so you have plenty of future in the processor. If you want to go AMD (My preference, less cost) then go with a AMD X2 series 5000 or later. The motherboard should match the processor type, but make sure that it supports PCI express x16 and it may be wise to make sure it supports more than 2 gb of memory. I don't think many, if any listed on the site have any problems running vista. Whenever you pick your motherboard, check what the maximum speed of memory it supports is and choose your memory by that number. As for your power supply..pick something 20(4) pins so it will work with any motherboard. *If* you invest in a 7800 or 8800 graphics card or greater, you will need a power supply 500 watts or higher. You can get away with 400 on anything else. Hard drive doesn't matter to much, but you may want Sata 3.0 interface.

If you have more than enough money to spend, I'd reccomend the new Geforce 8800 GT..which is running around 250 dollars right now. That graphics card will last you at least 3 years and it is currently a monster.