I don't usually condone this sort of thing but the providers have been incredibly tardy in releasing the Windows Mobile 2003 upgrade for the Motorola mpx200 so when I saw that a site was offering a download (and that there were lots of positive forum comments) I decided to have a go. This only works for Europe - so no GSM 900 support! Anyway, it seems to work perfectly, my phone is a lot more responsive and now I can have the .NET Compact Framework on my phone! If you want to have a go (and don't blame me if it kills your phone!) you can read about where to get it here.
Good luck!