Stay away from Tiger Direct. Their stuff is cheap because it's shit. You'll have a nightmare of a time upgrading and absolutely nothing on it is namebrand. A couple years ago I thought about buying one of those $700 paperweights until I did some research and found that their tech support is non-existent, their warranty is null and void after it leaves the warehouse (well not really but good luck finding someone who works there to acknowledge that you actually bought a computer from them), and did I mention the suck. You'll end up having nightmares trying to configure any hardware (IRQ's, new HD's, future soundcard, future vid card?).
I build my own computers so I really can't recommend a specific place to buy one. Some specs you may want to look at:
1.8a P4 - AMD XP-1600
CD-RW (12-10-32) Write/Re-Write/Read should be plenty
Mid-Size Tower w/ 300w AMD/Intel certified Power Supply
Cheap Soundblaster card (preference here on quality is up to you)
Cheap Video 2D card (32MB 3D if you play Unreal Tourney and stuff)
Ethernet card/modem (depending on your internet hookup)
256MB RAM
If you pay more than $700 for the above, you're getting ripped off IMHO. I don't mean to come off sounding harsh but what I have read about Tiger Direct and people I know that have bought from them, I can only say STAY AWAY.