Personally I’m seeing more and more people asking questions and being generally confused about building Web Parts with Visual Studio 2005 and .NET 2.0 for the current version of SharePoint. This is of course compounded by the fact that ASP.NET 2.0 has a class called WebPart, can do Web Parts but they’re completely different from the SharePoint 2003 ones.
My advice to you, weary traveller, is to simply don't bother with VS2005, ASP.NET 2.0 and SharePoint 2003 (WSS or otherwise) today. Yes, there are bloggers and MVPs out there that have instructions/sessions/presentations on how to do it however you can make it happen only under certain circumstances, and if you sacrifice the correct number of chickens (or virgins if you prefer) in the correct order on the correct night of the full moon. It's really just a big bother for very little gain IMHO.
Wait until later this year when you can just build stuff right out of the box. Trust me, VS2005 and SharePoint 2007 works like a dream.
Click, code, create.
No mess. No fuss.