Did you actually do an upgrade, or did you do a fresh install of Win8? Upgrades for Windows versions don't usually work well...
Sometimes it does. Years ago, I installed the release candidate of Win 7 and several of my favorite apps, including COH/V. Then, against MIcrosoft's advice, I used a few hacks and my company's volume license and DVD to upgrade that install to Win 7 Enterprise. All this time, I've been uing that same system and even added several extensive development environments such as Delphi Rad Studio (several versions), Visual Studio 2005, 2008, 2010, 2012, several video apps, DAW software, successive verions of MS Office fom 2003 to 2010, and of course some more games, notably cox, dcuo and CO. All worked with minimal issues.
Three months ago, I put Win 8 Enterprise on top of that existing build and my system works better than ever. I did have to uninstall 3 rarely used apps that were not compatible. But my rig boots in under a minute and is more stable than ever.