Don't mean to be repetitive, but once again, Dell.
I went shopping around for about 3 months before buying my computer, and no other manufacturer provides quality parts at such a good price. I compared Micron, Quantex, Gateway, Cybermax, and probably some other vendors that I don't recall before purchasing my cuurent computer.
Buying a computer at a retail store is the absolute worst mistake anyone could ever make when buying a computer, but I am sure most of you know that already. If you get a cheap system with a cheap processor, they will put all these junk parts in there. If you get a more powerful system, you may get better parts, but they will package it with tons of useless extras to make you spend more (video cameras, scanners, CD-R drives, TV tuner video cards, etc).
Dell is great because they pack their systems with trusted brand name products, not generic no-namers.