PC hardware: Build an old PC

look into a barebones unit

barebones make a good foundation for a 1st time builder. they include the motherboard, case, and power supply. you'll only need to add RAM, cpu, and hard drive to get started.

here's a nice one that could handle a celeron or low-end p4:
http://www.geeks.com/products.asp?cat=BBK
Here's another one that could handle dual cores: http://www.newegg.com/Product/Product.asp?Item=N82E16856110044

if you went for the dual core bb unit ($160), added a
2.6ghz dual core ($134), 1gb of ddr2-533 ram ($75), and 2 160gb drives ($150), you'd have a great general purpose PC for around $530 (assuming you already have an OS license). add a $100 PCIe video card for a decent gamer PC; add a $180 video card for a great gamer PC.

downgrading to a 2.8ghz celeron ($75) and a single hard drive lowers the price to only $400.

i've only mentioned intel alternatives. there are also amd barebones and you could build equally good (or even better) amd based PCs for the same prices.