Unreal is optomized for 128 mb of system ram. If you have any less, you will experience some slow downs, and occasional stops and droped frames. Try bumping down your resolution and use lower quality sound. This should help speed things up. Now with team apache, Im not sure... probably the same problem though, it is probably optomized for really high system ram amounts.
If you are running unreal at 800x600, drop the resolution down to 640x480, this should make it playable. I have to run it at 512x384 resolution with my Pure3d voodoo1 card, a pII 266 and 64mb of sdram mem. At 640x480, the frame rates are just too slow, and I have sound cut outs periodically. Try these out firts, but if 800x600 resolution is really important to you, get another 64mb of ram. Or get another 8mb creative voodoo2 card and run sli if yours supports it. (I know diamonds monster 3d 2 8mb cards support sli).