It probably wouldn't hurt to use the "Run as administrator" when installing it. I know I just put the DVD in the drive and installed it and it works fine. BUT. My FSX is installed on another drive ( J: ), well away from the C: drive and especially the C:\Program Files or C:\Program Files (x86). Most developers will tell you not to install FSX & Acceleration in the default location because of the strong protection W7 holds over those two folders.

Hope this helps.

Mark