What are some notable zd wads I can run on these systems?

[invictius]

Duron 900, athlon xp 2200, p4 3ghz prescott (s478). I'm buying an nvidia gt 6600 for opengl2 to give gz a go, but zd will also be run. Got a radeon 3650 but would that be useful for zdoom (I know it isn't in gz). Is there a rough date range of things that won't run even at 320x200? Or perhaps even a few wads that would be good as a stress test without crippling the system.