Walmart has returned the budget system for the old folks! It surfs (well, broadband unless you get a modem), it beeps, it has everything but a monitor, modem, or floopy floppy. Lindows OS. (Or put RedHat in it, that's what I would do).
17" Monitor for $119.86
$318.86 for a system, not too shabby. Though I think the custom budget system below is much better for you bucks:
Asus Terminator P4SC Barebones (Audio, Video, LAN, 56K, USB, Floppy, 52X CDROM). No AGP slot, though :(
20Gig, 7200rpm WD Hard Drive
Mouse, Keyboard, Speakers, 17" Monitor
$440 shipped, but not assembled.
Parts from Newegg. You could upgrade the barebone unit for $50 or so, that way you can have better video & an AGP slot to boot.