Okay, so I'm one of those GUI freaks that like using a GUI if it exists over the command-line. Lately, I simply use the ASP.NET IIS Snap-In to switch a particular ASP.Net application on a server to the proper .NET version. After installing the latest and greatest .NET 2.0, I still didn't see the snap-in. Argh... When searching the net, I found a pretty good post that describes how to resolve it. It says that the Beta 1 uninstall didn't clean up that well and thus some manual registry cleaning needed to be done.
Basically, you search for all instances of 40607 (the beta 1 build of .NET 2.0). When you find the keys, delete em. Also, you must nuke the following entry:
HKEY_CLASSES_ROOT\CLSID\{7D23CCC6-A390-406E-AB67-2F8B7558F6F6}
The forum post at asp.net says to reregister with aspnet_regiis -i. When installing the redistributable, I saw the command aspnet_regiis -iru run. The guys at Microsoft made sure the install didn't break existing ASP.Net (1.1) applications (which the switches -iru do for aspnet_regiis). Smart if you ask me. I can recall that the B1 didn't do that, and it raised concerns as I plan our 2.0 technology roadmap.