here i m writing the steps necessory to run upgrade utility on vista. You need to do this only once.
1. install some zipping utility like WINRAR.
2. Right click on the setup file of activesync 4.5.
3. Extract activesync 4.5 on any location.
4. Run Windows Mobile Device Center and click on Connection Settings.
5. Uncheck the Allow USB Connections and click OK.
6. Run task manager and go to services tab and check the services 'Windows
Mobile-based connectivity' and Windows Mobile 2003-based connectivity'
are started. If not, click the services button at bottom and go to next pop
7. Click the service name and press the 'play' button on the top bar.
8. Start Device Manager.Expand the 'Mobile devices' section and click
the 'HTC USB Sync.
9. Right Click and Update Driver Software.
10. Click 'Browse my computer for driver software on pop up screen.
11. Click Let me pick from a list of device drivers on my computer.
12. Click Have Disk.
13. Click 'Browse', and browse to the location where you extracted the
activesync 4.5 in 3rd step.
14. Double click wceusbsh.inf.
15. Select HTC USB Sync from the list and click Next.
16. Finish the installation process.
17. Run Task Manager Then find the WMDC.EXE and click End Process.
18. Now run the update utility and done ur update.
19. when you want to start syncing normally again run Windows Mobile
Device Center enable the allow USB connection as you disabled in step 5.