A While ago the following was posted on the Eidos forums. It should help people who are experiencing problems running IG on Windows 7.
Note: there's no way to play it without the patch
Let's start. First, we have to install the game. But not in the usual way. We don't have to open the autorun, and if we have it open let's close it. What we need is to find the file called Setup.exe inside the CD; to do that go to explore the cd/dvd drive and look for the mentioned file. Then right clic on it -> Properties -> Compatibility > Select the option "Run this program in compatibility mode for" and select windows XP (service pack 3). Apply changes > OK, and then run setup.exe. After the installation of the game, it's necessary to install the patch. Once it's done, we have to go to the root file of the game where it is installed and find the file ImperialGlory.exe. We have to do the same we have done with the file setup.exe. Finally we are able to play the game.
The only issue I got is random "flashes" on the screen, but believe me, they are not so annoying to prevent a gamer to enjoy this game.