Storage points are explained in http://www.worldcommunitygrid.org/forums/wcg/viewthread?thread=1505

By default, you authorize the WCG to use up to 1 gigabyte (GB) of storage on your hard drive. Actually, the current Human Proteome Folding Project fits within 50 MB. You can sign in and change your profile to use more, if there is enough space in your partition. The maximum allowed is 10 GB. Because of the difference between 1,000,000,000 bytes and 2**30 bytes (different definitions of gigabyte) a gigabyte authorization is computed as 0.98 gigabytes.

Your authorized storage must be in the same partition as your WCG program. You can try moving the WorldCommunityGrid subdirectory from C:\Program Files to another partition as long as you replace the Startup shortcut with one to the new location. I have never done this. But it sounds as though you do not have a partition with 10 GB available.