Such emulators usually use old methods of memory allocation, the basic problem may be that they are DOS-based programs that are notorious for being highly incompatible with Windows XP. You may try running the emulator(s) through a DOS emulator such as DosBox. Drive a google search, you'll easily come up with DosBox. (It's not something I fully tried, by the way). Maybe that helps, just an idea..

Sid Meier?.. Oh well he is rightfully enjoying what he earned from the best strategy game around : Civ4. Thanks to Lord for his genius presence in game market (What a prayer..)