I'm just going to start off saying that I've installed Visual Studio 2005 almost a dozen times on Windows Vista with no issues... Tell today.

My company recently gave me a laptop to use so naturally the first thing I do is blow it away and install Windows Vista Ultimate on it. After the fresh install do the windows update, install Office 2007 so I can check my email and then I proceeded to install Visual Studio 2005... To my surprise it fails telling me I need to install Windows XP Service Pack 2. So after a short WTF moment I start to run the setup in all the compatibility modes I can find with no success, I guess I'm off to search the internet (Weeee!).  So after an hour or so of finding nothing I finally come across this form posting: http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=1186197&SiteID=1

Now I was getting excited, this looks like the fix. I follow its instructions and edit my registry to trick the setup into thinking I'm running Windows XP SP2. Then I run the install again to see if it'll work and it does.  But then I get the next error talking about MSXML 6, this was a little disappointing but I was ok with it because the same forum post mentioned a fix for this as well. So I go back and follow the instructions to install DExplorer then go back to my VS 2005 setup. Everything's looking good and then... Failed... same MSXML error, I try rebooting just in case there is some COM registration issues going on, try again... same error. So now it's back to the internet to try and find another workaround and ended up coming up with this forum post: http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=73806&SiteID=1

Even though this was for Vista beta 1 I thought I would give it a try, I copy all the files locally and... no success. At this point I'm becoming extremely frustrated and start venting to my co-workers and one of them (Fabio for those that may know me/us) suggested that I should try installing it under another user profile so at this point I give it a shot. And it works!!! The only difference between the users is one is a local user the other (that didn't work) was a domain user but both are local administrators.

Now this leaves us to wonder if I would have had to go through all of the other crap or if everything would have worked find had I used the other user from the get go...

Hopefully this information may be useful to someone and I help you save a couple hours of pulling out your hair...

Read the complete post at http://dukk.org/blogs/justins_development_adventures/archive/2007/05/02/visual-studio-2005-vista-install-nightmare.aspx