Well, I'm upgrading from Beta 1 to the December CTP, since my friend (who works on VS) insists that it's 150% better than the Beta. We've run into some issues, and I hope that December CTP will solve them (since no Beta2 was released today, as far as I know :)).

I was getting an error: 1304 Access denied on SdmCompile.dll. It tells me to check the path, but doesn't provide a path. Searching the whole system didn't find it. So, I went into the DVD and tried to install the .NET 2.0 Framework by itself - aha! It said “A previous product is installed....”. Even though I had already uninstalled everything.

All help pointed to a tool called MSIINV.EXE. Well, that's not public, and I didn't feel like calling PSS (why it's such a dangerous tool is beyond me, since MSIZAP is available). Reading some blog posts, I see that the suggestion is to find the .NET Framework, J# redist, etc. etc. for .NET 2 using msiinv.exe, and then msiexec /x or msizap TWA them.

Well, as far as I can tell, it just looks at HKEY_CLASSES_ROOT\Installer\Products. Maybe I'm wrong. But that worked for me. Regedit, goto HKCR\Installer\Products, and then search for anything related to the 2.0 Framework and friend. Find the product code, then run MSIZAP TWA {XXXXXXXXX-XXXX-XXXX-XXXX-...}. The format is important! If you just copy from the registry, and don't do 8-4-4-4-rest, it won't work.

After I've cleaned everything, I think installing the .NET Framework 2.0 and the J# redist (arrrg) separately from the VS install helps.

Just my few bits on getting VS working. A lot of others have posted too, so doing this plus what everyone else suggests might work :).