You probably have an asus board. When booting up your system, hit the pause key and write down the bios version (at the top) and the serial number (at the bottom) to verify your mobo specs. You may be able to run a thunderbird 800 or 850 slot a. Personally, if I had a slot a system, I would sell it in the local paper and start over, with systems being so cheap. You can get an xp generic system with win98 or other operating system for about $400 (inclucing shipping) on pricewatch. Cheaper than upgrading.