I've been running IL2 (and Hyperlobby) on both the Windows 7 beta and the RC, and I'm now running on the final version (RTM) and it works great (x64 Ultimate).
As said earlier you have to use a.exe to install IL2 1946, and do NOT install it into the default "Program Files" location (I've heard, never install games there myself anyway).
There are also some quirks to get Hyperlobby running, beeing programmed in Visual Basic 5 from the stone ages

The RTM version seems to have the UAC settings a bit tighter than the RC (UAC is User Access Control - the questions that pop up demanding Admin rights etc). First of all you have to run the setup file with the right click option "Run as Administrator" to get the installer to work. Then you have to set all the different exe-files (aping.exe, dexec.exe and hlpro.exe) in the install dir to compatibility mode for Win 98 (XP is not enough!, I think it was enough in the RC). The app will look a bit weird (more than usual) and the "x" for closing the app will be hidden etc (at least on my Nvidia 275 GTX). A note, If you only set hlpro.exe to compat it will run, but you will not be able to save the location of the "il2fb.exe"

Good luck /Mazex