Since going over to W7 it has been an expensive transition. Firstly I had to change the wireless LAN card, sound card and graphics cards, as none of these would work properly in W7.
I previously had GE ProII and Active Sky 6.5, Ultimate Traffic and other add-on programmes - yet again these had to be replaced as they would not work. I now have to check with every add-on if it will work in W7.
That said however I am starting to see the improvement. I now have a clean FS9 which I am building up slowly still, but the flights I have run so far have been a lot better, with sharper images and smoother running (could partly be due to the new graphics cards as well!).
Pete, with regards to the registry in XP, I did the following to improve performance:
From the Windows desktop:
Press START then RUN
type REGEDIT
Browse to:hkey_local_machine\system\current controlset\control\filesystem
add DWORD NtfsDisableLastAccessUpdate
Change value to 0X1
Now reboot your system.