After installing VS2005 SP1, I attempted to install ReSharper 2.5 (build 236) and was presented with the warning dialog ( below).
I had previously installed the hotfix when installing v2.5 build 301, so I assumed VS 2005 SP1 includes the hotfix and that the VS service pack setup removed the original one that ReSharper setup is looking for. Taking this leap of faith, I chose the "No" option. Everything seems to be working O.K with regards to the colors.
Perhaps a fix to the ReSharper setup to look for either VS 2005 SP1 or the hotfix before presenting the warning dialog would be a good idea?
Dialog from ReSharper setup.
For ReSharper to function properly, you need to have the official hotfix for Visual Studio 2005 installed.
ReSharper setup program could not detect the neccessary hotfix, and is ready to perform the update.
Would you like ReSharper to install the hotfix now?
If you press "No", the ReSharper colors may not display as intended.