If you're on 2003, WMP is suprisingly ace.
I find that it can compress files comparable to Divx, and offers 2 pass encoding. Futhermore, it doesn't have a problem achieving 320x240 30fps on my measly little iPAQ 1945.
A friend of mine recently upgraded his 3955 to 2003, and verifies the same increase in playback performance.
As much as I hate M$, their player does finally do it's job.
My only problem with PocketMVP is that it doesn't sustain peak FPS as well as WMP does on high bitrate files.
