The $600 dollars or less, really depends on whether you or someone you know can put a computer together. If you don't, heck hard to beat $600 bucks. Does that come with a Keyboard and Mouse? Also I think AMD has a Duron 1200 now, was that the Duron or T-Bird.
Here's a quick list I put together. It's a lot more rock solid as well. IWill Motherboard, with DDR. And a 7200 RPM 40G Harddrive. Heck I think I could beat these prices even further on www.pricewatch.com as well. These all come from www.compuplus.com. You can beat the memory price from crucial.com and they even have free 2 day shipping right now.
3Com/USR V.90 3595 PCI Internal WinModem OEM $24.00
Linksys LNE100TX EtherFast 10/100 PCI NIC with WOL $5.99
Iwill KA266 PLUS DDR Socket A Motherboard 266FSB - Retail Box $92.00
VisionTek TNT2 M64 32MB Graphics Accelerator $43.00
Sony 1.44 Floppy $12.00
Enlight Mid-Tower ATX Case with 300 Watt Power $47.00
Pioneer 16X DVD Tray Load White Box $75.00
Maxtor 40 GB 7200 RPM ATA100/133 $92.00
AMD Athlon Thunderbird 1.2 GHZ 266MHZ FSB RETAIL $126.00
Major Brand DDR 256MB PC2100 $58.00
$574.99
now the downfall is, compuplus is a little more pricy in shipping that's another $100, so about...
$675 total, for a much much more rock solid machine and faster. You could even upgrade the video to a Hercules 3D Prophet 4500 Card, which would be a massive upgrade for only $27 more. And you could upgrade the case to an Antec, which would give you more room and airflow for about $9 more. So now after shipping about $711.
I know if you were willing to buy from 2 or 3 sites from www.pricewatch.com instead of 1, you could get that to about $600 or a little over with shipping.
With all that said, the machine your friend would be getting i'm guessing is good enough for quite awhile. But if you really want a good, kick butt one for the same price...build