PS: For those who usewindows 7 and VC6; I had problems getting the actual setup program to workproperly. Instead, I updated it manually. To fix the Add->Files problem,make sure you are NOT running any part of Visual Studio 6.0 and make sure alsoyou dont have any files open either local or over the network (on the safeside, just disable your network). Then you can fix it by doing this:
Download and Unpack the VC6 SP6 into a dir like C:\INSTALL
Locate VS6sp61.cab and open it with an archive editor (I use winrar)
locate the subfolder common\msdev98\bin in the archive
Assuming your VC6 is installed in c:\program files\microsoft visual studio, go to this folder in explorer "c:\program files\microsoft visual studio\common\MSDev98\Bin"
Backup all the files and folders in this directory before proceeding, I just put them in a .rar file just in case something went wrong.
Now, select all the files and folders listed in your archive program‘s file view (you should still be in the folder mentioned in step 3).
Drag them or extract them to the folder mentioned in step 4.
When asked, make sure you confirm that you wish to overwrite the files (do for every one or use checkbox at bottom).
Depending on what suite of VS6 you have, you may need to delete msdev.exe and rename one of the msdevP.exe or msdevS.exe. If you are using Enterprise Edition, you dont need to. My guess is that msdevP is for Professional Edition and msdevS is for Standard Edition.
Once you have done all that, start visual studio and open/create a project. Then try project->add->files, you should be good to go. Remember this method works for Windows 7 x86, i dont know if it would work in vista or in x64 versions.
Hope this helps someone - I feel that since I know about it I should share it since it isn‘t an overly obvious alternative and if reversed I would hope others would do the same.