Tom's Hardware Guide
Tom's Hardware Guide, was one of the first hardware guides with gamers needs in mind.  He's the main man when it comes to computer hardware.

Anand Tech
Anand's Hardware tech page is another great page that's updated on a daily basis with reviews of just about every thing.

Cyrellis
Cyrellis has some cool previews, like the Riva TNT and some of the best reiviews and articles around.

Pricewatch
Pricewatch is the only site for buying hardware for your PC. Its basically a price search engine for PC hardware. I go here to find out where to buy my parts when assembling a PC and so should you, so check it out.