This is a fix straight fromt he microsoft help site. The page is here
http://support.microsoft.com/default.aspx/kb/927007.
This is the second last fix int he list, it may help with activation.
THIS WILL REQUIRE YOU TO ACCESS THE REGISTRY. IF YOU MAKE A MISTAKE YOU COULD DAMAGE YOUR SYSTEM. CREATE A RESTORE POINT INCASE1. In Windows XP, click Start, click Run, type regedit, and then OK.
In Windows Vista, click Startthe Start button, type regedit in the Start Search box, and then click regedit.exe in the Programs list.
User Access Control permission If you are prompted for an administrator password or for a confirmation, type the password, or click Allow.
2. Expand the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CURRENTCONTROLSET\CONTROL\CLASS\{4D36E967-E325-11CE-BFC1-08002BE10318}
3. After you find the folder, double-click Upperfilters on the right side.
4. Change the value from 0 to PartMgr, and then click OK.
5. Close Registry Editor, and then try to use the activation wizard.