I've started seeing google queries where people seem to be having issues with Visual Studio loading slowly. There are a few things that could be causing this and some things you can do to help. 

• I've talked a lot previously about various issues with virus scanners in the past.  You might try turning it off temporarily to see if that is indeed your problem. Also read my post for more information. 
• Startup settings: If you have VS.Net 2002 simply ensuring neither the start page or the dynamic help window are opened by default will shave several seconds off of the load time.  In VS .Net 2003 we fixed these problems for you.  But if you defined a custom start page in either version that causes IE to load you will incur the wrath of loading IE before VS will become usable though. 
• Network Issues: Yes, some people have posted that disconnecting the machine with VS from the network will speed up launch time.  No, we are not secretly uploading your source code to Microsoft servers. This is a bug with the MRU functionality and files access over the network.  You could go into the registry and clean out the VS MRU locations that are stored here:
  • HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\7.1\FileMRUList
  • HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\7.1\ProjectMRUList

Or you could download the VSTweak Powertoy I created that will let manage these lists yourself like Alex Chang did.  It lets you change a bunch of other stuff as well, but strangely enough this seems to have been the most requested functionality when I was writing it.