OK, so there's no rush, then.
You should still go ahead and sign up for both the Live Search Cash Back program and the Newegg newsletter. Live Search cash back can save you money on all sorts of things besides computer components.
I'm going to warn you that I doubt that any system built from separate components will be any cheaper than the setup I posted above. That Dell is really that cheap. The advantage will be in the quality of all of the components and the fact that they will come with a longer warranty from their respective manufacturers free of charge. I'll try to find as many components as I can with a lifetime warranty as well.
I stand by the monitor recommendation that I made above, however, in spite of its one-year warranty. You're just not going to find a better deal on that grade of panel anywhere.
List of components:
Motherboard: ASUS P5Q PRO
CPU: Intel E8400
Memory: We'll cross that bridge when we come to it. As long as your motherboard supports it you've got nothing to worry about.
Hard Drive: Western Digital WD6400AAKS 640GB
CD/DVD Writer: I can't really make an educated recommendation here. I've always used LiteOn, myself.
Video card: Nvidia GTX260 Core216 -The best deals around are on these right now, and contrary to what I said above, they are
worth the extra cost over the base GTX260 because they're only about $25-$30 more. Of course, this is subject to change at any time.
Power Supply: Once again, we'll cross that bridge when we come to it. It should have ~40 amps on the +12v rail. I prefer those with long warranties of 5 years or more.
Monitor: See my above post.
Case: The only recommendation I can make here is not to go overboard. You can get a very decent one for $50-$60.
Peripherals like keyboard, mouse and speakers: You can't go wrong with Logitech.
Depending on the deals available when you're ready to buy, all of this should come to around the same price as the Dell system and components listed above, give or take $100.00. Expect to spend around $1000.00 for all of it, including a copy of Windows XP.