[rdouglass]

I have done this at Tigerdirect.com many times. They have very reasonable 'barebones' units that you can generally add whatever you want to them. Their barebones units usually come with a case, PS, matched CPU and mobo, as well as RAM; usually a good place to start and then add your video, HD, etc. to taste.

You also don't need to buy any OS with them but you can if you wish.

I have been quite happy with them.