Need help with building new comp

trying to build a cheap gaming comp for my brother he says he has the os and hd so was wondering if you guys could help me out

Video card - $100 - Radeon HD 4850

http://www.newegg.com/Product/Product.aspx?Item=N82E16814102770

Memory - $52 - G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231122

Processor - $168 - Intel Core 2 Duo E8400

http://www.newegg.com/Product/Product.aspx?Item=N82E16819115037


I dont know what a good cheap motherboard or powersupply are to go with those or if it would be cheaper for me to build a amd system if you guys would change anything please tell me

On a cheap budget system I like this dual core CPU and Motherboard.It's not quite as powerful as the E8400 but it is a lot cheaper.
A fast 3.0 Ghz dual core CPU and a quality new motherboard with nice features at a very low price.It will only be available as newegg only offers these combo deals for a short amount of time (usually about 2 weeks at best so as this combo has been offered for about a week the sale will be over pretty soon).The motherboard here uses DDR2 RAM by the way.This deal is a steal really ($140 for the CPU and Motherboard).

http://www.newegg.com/Product/Comb [...] mbo.237632

Most atx cases will take micro atx boards.Just look around for other combo deals on CPU's and Motherboards at newegg but that one is hard to beat.In fact I am going to order that combo for myself perhaps by tomorrow.