I also experienced issues with Windows Update searching forever for updates when Windows Update 7.6.7600.320 was automatically installed after updating the system to SP1 (this was after doing a clean install of Windows 7).
The following worked for me:
1. Manually install KB3083710
2. Manually install KB3102810
3. Restart computer
4. Run Windows Update Diagnostic Tool in order to reset Windows Update (support.microsoft.com/en-us/kb/971058)
5. Restart computer again and search for updates