My daughter has been using our hand-me-down Gateway computer. It's been fine for what she's been doing, but it doesn't have enough graphical oomph to play Zoo Tycoon 2. I thought about just putting a new graphics card in it, but since it's only a 500 MHz cpu, an upgrade seemed to be in order.

Off to NewEgg. I've built two computers from scratch with their parts, and didn't expect any problems. Here's what I bought:

13-135-160 MB VIA KT333| K7VTA3 V6.0 ECS
(Serial#: 996640E40103202)
1
$33.00
$33.00
For Tech Support Please call 800-829-8890
 
14-121-506 VGA ASUS|RADEON R9200SE/T/128M TV R
(Serial#: 610839010578)
1
$48.00
$48.00
For Asus Tech Support, Please Call 502-995-0883 or http://helpdesk.asus.com/
 
19-104-201 CPU AMD|SEMPRON 1.5GHZ SDA2200DUT3D
(Serial#: 19405279)
1
$48.00
$48.00
For Retail AMD processor, please call 408 749-3060 for service after first 30 days. For OEM AMD processor, we will service for 30 days only. Please verify the Processor matches your order Prior To installation. IMPORTANT: Always pack your CPU well for return. We will refuse your RMA if we received it as DAMAGED!
 
20-141-302 DDRAM 256M|DDR333 PC-2700 -K %
(Serial#: 740617064582)
1
$34.23
$34.23
Kingston Support: 1 (800) 835-6575
 
35-124-003 CPUFAN KINGWIN KCU-7015 (INTEL/AMD)
(Serial#: 856149000445)

The total was $185 and change, including shipping.

The Sempron is AMDs replacement for the duron line. We used the existing disk and case.

Sam helped a bunch at pulling the old components out of the case, and in putting the new mobo in the case. Unfortunately, doing a motherboard swap on a non-generic case is a bit of a pain, as it doesn't have an I/O cutout for the new plate. [Update: David asked whether there was a I/O piece with the mobo. There was, but the Gateway case didn't have the cutout - just a big piece of metal that had the appropriate holes (for the old mobo) in it].  It took me about 30 minutes with the dremel and 6 abrasive blades to cut out the slot, and then the mobo went in the case well. Hookup was easy, except for the front switches and lights. All the wires wire in a 2x6 connector rather than the separate connectors you get in a generic case. I didn't have any luck relocating pins nor did I have any extras (connectors I had, but none of the pins that go in them), so I settled on hacking in the power switch connectors to a ribbon cable connector I had lying around.

Got that done, hooked up the disks, turned on the power, turned off the power, fixed the master/slave on the disks (they were on separate channels on the old computer), rebooted, installed XP, used the board jumpers to set the FSB speed (who uses jumpers for that), got all the SPs and drivers installed, and the thing is up and running quite nicely.

A pretty nice upgrade for the price.