Monitor, screen resolution, and OpenGL

Hey, I've been trying out many linux distributions in the past month or so, and I decided to try Mepis yesterday. It looks well-done and all, but I am a linux noob in general, and have a couple of questions.

First, I like to run my x screen resolution at 1280x1024, and I know my video card (voodoo3 2000 agp) and monitor can handle it, but KDE won't let me go above 1024x768. I have changed my monitor type a few times, restart X, but I don't get any higher choice than 1024x768. This isn't a big deal, but I'd sure like to run at a higher resolution.

Next, probably due to some video card driver or something, my opengl in X sucks. Even the screen savers draw very slowly. The only linux distro which used my video card for open gl well was Alinux. I would have stuck with that one for that reason, but it was kinda quirky. Mandriva works about the same as Mepis when it comes to my GL. I'm not sure how to set it up to work properly if it's not the driver. I'm pretty sure Mepis is using the same driver as Alinux, just going by the name of it. I'd really like to be able to play me some Unreal Tournament GOTY in Mepis. Is Mepis only set up to run GL with Nvidia? I know linux in general is Nvidia and ATI, but Nvidia bought out 3dfx (who made the voodoo I'm using), so I dunno. Maybe that doesn't matter.

Anyway I would appreciate any help you good people can offer. Thanks

~LiNoobux