Anilrgowda

Weblog J2s site has put together a hardware list capable of running Vista in all its Aero glory for just over $500.
This setup should run Vista and pretty much any regular application you need (it won't necessarily be ready to do anything but light gaming, but hey - we're not all gamers). All you need to do is put it together. Luckily, we've covered almost every step of building a PC here at Lifehacker, from installing your motherboard, CPU and RAM to your hard drives, PCI cards, and power supply.
Granted, taking the DIY route with PCs is sometimes a touchy subject, since you can always get cheap PCs from suppliers like Dell for bargain prices, but if you're keen on doing it yourself, building can be a great way to get to better know your system (I know I learned a helluva lot when I built my first PC a few years back). Also, the cost of Vista isn't included in the $500 price (Home Premium is linked in the article for $115) - which is always another point to keep in mind if you choose to build rather than buy.

Source:Build your own Vista PC on the cheap - Lifehacker