But I still have to figure out how to solve the problem

The biggest problem is, that after having purchased TrackIr - I can't enjoy FSX without it

Installing SP1 did not install the new flightsim folder, in WinSxS?I too have wasted much time on this with vista 32.
You have to right click on the folder, go to properties, security, take ownership of the folder and give yourself full control of the folder, otherwise you can't delete it.
I also have had the same problems with the simconnect folder on installs/uninstalls. Just today I've installed an entirely new version of fsx after deleting everything, absolutely everything to do with previous installs of fsx and simconnect. With me too it didn't install the simconnect folder, so I had to manually insert a copy of the folder that vincent had kindly sent me in the sxs folder.
Then when I installed sp1 (as I have before and it installed an extra simconnect folder) this time it didn't instal the extra folder!?
All very confusing. Does a copy exist of the folder that should install with sp1?
Leighsky.