I'm frequently asked to give suggestions for computers and equipment.
here are some useful links I use for shopping:
Dealnews.com is a good site for various things, like timely deals on computers from dell, hp, etc. Also good for electronics. They have some other associated sites, dealram.com, dealmac.com and more.
Pricewatch.com is a good source for OEM and other cheap computer parts. broken out into categories, and ranked by price.
I also use this forum posting from overclock.net that ranks video cards. Coupled with pricewatch, it is a great way to shop for a video card upgrade.