See this link, it says everything perfectly.

Additional thought: Don't install in the Program Files folder because Vista puts additional security limitations on all files and folders in the C:\Program Files\... directory tree. You'll have to take extra steps to get Folding@Home to run from that location in Vista. Try C:\FAH, for example. One of my quads uses D:\FAH1, D:\FAH2, D:\FAH3, and D:\FAH4. ~sorto'