The MGS folder in ProgramData has never been removed after uninstall Microgaming. The MGS folder in the ProgramData is the largest in Windows 7 and 8. Microgaming need to fix that problem in the uninstall program to tell the uninstaller to remove that. At the moment it does not.
Although I would advise people not to play with any registry entries except professional or expert who knows a lot about registry can do that. Registry is very tiny file size to compare and is rendering useless when removing registry. I found that people play with registry can get a serious consequence on Windows operating system corruption. If you want to use registry cleaner to remove automatically for you, make sure you only choose in the tick list of microgaming that is related to that with name of microgaming to remove that registry and leave the other alone.
I use Iobit uninstaller 2013 and they have powerful scan to search for trace of it that is left over that uninstaller did not do so. I choose in the list of trace which to remove that is relating to software I am uninstalling. (It does search for rest of trace of files and registry). Although just to be careful that if after you uninstall software and it tells you to restart, it is best to restart first and you won't be able to use powerful scan that in some of case. Cos when restart it helps uninstaller to remove the rest of it.
I think its time for us to lodge it to microgaming to fix the uninstaller to ask the uninstall program to remove MGS off ProgramData. That would save us hassle and fiddle around.
Rubbish.... deleting MGS and Microgaming in regedit has never affected my pc.