I'm running AMD 2400xp, with 512 pc 2700 on a Biostar NV2-ultra 400 board(the cheap generic one). Nothing is overclocked and I'm using all performance settings in my driver settings. I get an average 3dmark 2k3 score of 5300. So yes, you are getting a low score. Most likely you have AA and/or AF set high and quality settings. Also check to make sure you're not running alot of useless background apps at startup, like chat clients or media players.
If you're running xp try going to this websight:
http://www.blackviper.com/WinXP/servicecfg.htm
Good tips for tweeking an XP gaming machines settings. I always use the SAFE settings and have yet to have anything not work properly in XP with games or any other app(other than known bugs).