How to have separate installs of PA and SH2
Author : Hitman ( copied directly from his post)
You can have multiple installs of SH2 in the HDD, but they all will share just one registry entry. If you have already PA installed and do not want to deinstall it (Which would be the best procedure), the easiest way to go is as follows:
1.- Create a new folder and name it f.e. "Pacific Aces Dedicated Install", or anything different to what you had already
2.- Copy the whole content of your current PA folder into this new "Pacific Aces Dedicated Install" folder (Right click, Select all, copy, paste)
3.- Deinstall from your Windows control panel the SH2 and PA install. It will kill the old install, but since you have copied everything to your "Pacific Aces Dedicated Install", nothing is lost in reality
4.- Now reinstall SH2 from your CD, of course elsewhere of your "Pacific Aces Dedicated Install". The registry key created by this install will already work for PA, but note that you will not be able to select 1024 res in PA now unless you install the hi-res kit also to Sh2. The reason? In the registry key there is an entry for the available resolutions, and stock SH2 does not have that 1024. Also remember that using 1024 in PA and then starting stock SH2 will result in a crash, because SH2 will not be able to find a 1024 res when playing SH2.