Well the link doesnt seem to be going through right now, but i looked at it earlier today...looked pretty good. I don't think you had an OS listed there. If you are gonna run XP, not much difference between 2 gig and 4 gig because you are limited to 3.25 gig minus your PCIexpress video memory, so you will be in the 2 - 3 range anyway unless you run a 64 bit OS.
A site like that where you can customize whithout getting raked over the coals is nice in the 400 - 800 range. They will put together a nice PC that you can actually upgrade the motherboard in, in the future.
As always....I urge people to check out
www.dealcatcher.com and check out the Dell deals. You can get some sick deals sometimes where they throw you a flat pannel for nothing. But, you get stuck with Dell support for parts and with Vista...so pick your poison.