I've seen a few failures with MSXML6 on machines with Beta 1 bits on it which weren't fully cleaned up.

If you run into this, first, try using the Beta Clean up tool at:

http://go.microsoft.com/fwlink/?linkid=47065

If you're still encountering the issue, try the following workaround:

1. cd c:\windows\system32

2. rename msvcr80.dll msvcr80.dll.old

3. Run wcu\MSXML\msxml6.msi.  It installed fine.

4. rename msvcr80.dll.old msvcr80.dll

5. Run setup.exe to install VSTS 2005.