[citation][nom]beayn[/nom]Then something is wrong with your hardware, or yourself. If you have these sorts of problems on clean installs with no internet, you're doing something seriously wrong and should probably stick to Macs as you've implied. The odd badly written program might cause this, but that can happen on any system and is usually fixed quickly with a patch if said company wants to stay alive.
Again, hire new IT people because the ones that let their networks get like that are idiots, and this has nothing to do with PCs, hardware or software.[/citation]
If you check Steam's forums, there are still complaints about some of Valve's games, such as TF2 or HL2, having issues with the DEP. Valve also specifically stated that DEP should be disabled for TF2, though Windows doesn't allow HL2.exe to be excluded.
You also forgot about the management. A computer-ignorant superior (or a group of them) can easily deprive the tech department of funding or just being a roadblock.
"Why upgrade from Windows NT 4.0 to Windows 7 if the NT still works fine?"