Unless you really enjoy programmatically creating user interfaces and like the sound of 'Web Part Definition files', there is a much simpler way to develop custom web parts for use in Share Point websites...
A bunch of thoughtful guys have put together a container application which you can drop regular ASP.Net user controls into so they can be used in a Share Point website. The same container also exposes the Share Point namespace so this can be manipulated from within your own user control.
All you have to do to use this is download and install the container application called SmartPart:
http://www.microsoft.com/belux/msdn/nl/community/columns/u2u/smartpart.mspx#What%20is%20the%20SmartPart?http://www.smartpart.infoHow smart is that?
Will