Do you want to build this yourself or do you plan to just customize one online and have it prebuilt?
If you're looking for prebuilts then I'd go either with Dell if you have trust issues(they have good deals with LCDs too), or with www.ibuypower.com
If you're building this on your own, I'd go for:
Intel Core 2 Duo probably E6400
7900GT or higher video card
Not sure about RAM, I haven't looked into DDR2 since my system still uses DDR, but Corsair always has some decently priced value ram, aim for 2 gigs, anything more than that is excessive for now.
Case is up to you
Power supply, get this from OCZ or FSP or Enermax, spend about 100+ on this, don't want to skimp out on this
Optical drives are up to you, lots of people have these lying around, but if you don't the Samsung 18x DVDRW w/ Lightscribe is nice
Motherboard, not sure about chipsets and everything anymore, i've been out of the loop for a while, last time i checked 680i was pretty nice though...
LCD get a viewsonic or something, I'm using a Dell LCD right now so I haven't had much experience with much else.
yeah.. i don't know if i forgot anything, i'm in a rush so I can't get you links or look into this more, but i hope this gives you a nice start to things.