Darn, wish I'd seen this thread a little earlier. I had essentially the same constraints - around 600-800 (including monitor). The only difference is that this is specifically a system 'for the kids'. I fiddled around on newegg for awhile, then came across this dell one:
http://configure.us.dell.com/dellsto...=DDDWDD3&s=dhs
Which seemed pretty good for $700.
Damn you, dell.
(The link probably won't work forever, so here's the specs:
Intel® Core™2 Duo Processor E4500 (2MB L2 Cache,2.20GHz,800 FSB)
20 inch E207WFP Widescreen Digital Flat Panel
2GB Dual Channel DDR2 SDRAM at 667MHz- 2DIMMs
320GB Serial ATA Hard Drive (7200RPM) w/DataBurst Cache™
16X DVD+/-RW Drive
Integrated Intel Graphics Media Accelerator 3100
I probably could've done better self-building, but I'm no longer 'up' on the hardware enough to be certain of not screwing it up. I didn't even think of asking here on TFP. The CPU could be a little faster, and the video is of course just intel. But the kids aren't into the 3d games yet, so anything more at this point would be a waste. Plus, 20" monitor - damn.
I probably could've gone with lasereth's wishlist, pulled back on the video card a bit, and slapped a decent monitor on there and still stayed under $700. Ah well.