I'd say try to play them in XP Mode if you have a CPU with VT, but I don't think hardware acceleration or something along those lines works with XP Mode, i.e. graphics intensive programs. If changing the compatibility didn't work, you may have to do a dual boot set up unfortunately.
Also remember that some old games do not work right(freeze/crash/slowdown/ect) with multi-core/multi-cpu systems. This means you may have to patch them with a program like setaffinity or change the affinity in the task manager if the game at least starts.
Ok this is weird, deus ex works fine, but Sshock2 is troublesome. I've downloaded the SStool from strangebedfellows, a site built on SS2, which patches and adds bug fixes and its pretty random outcomes. I got it running by patching it, but with nothing else, no compat mode and only run as admin ticked, and it worked perfectly (win7 auto sets affinity to 1 core).
Then, i added bug fix, and it just crashed to black screen. I uninstalled and reinstalled it, and just applied the patches, and now it wont work at all.
I went looking in my registry to delete any remnants of it and reinstalled, and it still crashes to black screen.
I reinstalled it a 3rd time, this time with no patches, and now it just crashes on start up.
I'm trying to remember if Deus Ex and System Shock 2 were DOS games? If so, DosBox works wonders! It's how I get games like Duke Nukem 3D to work.
In fact, if you purchase your games through Good Ol Games (www.gog.com), they package DosBox right into the install package for you for all the old DOS games they sell (Gabriel Knight 1, Phantasmagoria, Duke Nukem 3D, etc).