there is only 1 stop to make when buying computer parts. That would be http://www.pricewatch.com.
They categorize lots and lots of websites and the prices they have for various parts, and allow you to see who sells those parts for the least cash. It is at pricewatch that I found out that http://www.pcboost.com
was selling 512MB PC2100 DDR memory card for a mere 45 bucks. No shipping and handling. That's the cheapest price for the most good ram you can find anywhere. http://www.pricewatch.com
is THE place to go. Everything else takes second place.