UT2K3 demo does not work for me

. My computer is crap. I don't meet the minimum requirements, so that's that. It crashes on startup, but if I do a benchmark startup, it gives me this error:
UT2003 Build UT2003_Build_[2002-09-13_17.31]
OS: Windows 98 4.10 (Build: 67766446)
CPU: AuthenticAMD PentiumPro-class processor @ 499 MHz with 127MB RAM
Video: Voodoo3 AGP (666)
Assertion failed: RenDev [File:WinViewport.cpp] [Line: 536]
History: UWindowsViewport::OpenWindow <- UGameEngine::Init <- InitEngine
Overall, it means that my computer can't handle the engine. I got the same error for America's Army. I'll be building my own computer in about 2.5 months, so I'll be playing it then. As for Battlefield 1942, Sponge, you don't get it, I CAN'T play it, it doesn't even open. It says "Cannot match minimal videomode" and crashes. I've just been playing Medal Of Honor: Allied Assault over and over again, and it runs really bad too, 10 fps or less. Even Return to Castle Wolfenstein runs at less than 15-20fps. I can't wait til I get a new computer!!!! I need it before Doom III comes out, I NEED to play that game!!