Installing Beta 1 of Service Pack 1 of Visual Studio 2005
First off, save time and the headache, do it in a virtual machine its a Beta! Heck do all your dev (if you can) in a Virtual Machine.
Be warned that it took me about 40 minutes from start to finish. For the entire installation my machine was very sluggish and the UI for the installer was pretty slow and sometimes seemed like the entire installation and machine was dead.
Steps for installation:
1. Start the installer, Go for a coffee.
2. Come back in 10-15 minutes, Hit OK and accept the EULA, go for another coffee.
3. Come back in 20-30 minutes, reboot the machine.
I created a bug/feedback item just for this, vote on it if you feel the same as I do.
https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=213096