The "default" installation folder for (any version of) Windows
installed on the partition X: is some subfolder of "X:\Program files".
So in Your case, programs installed from XP will set "C:\Program files\..."
as default path, whereas those installed under Win7
will set "E:\Program files\...". But for most programs
You can choose yourselves an installation folder different from the default one.
that has nothing to do with that stoff the thing not working worked unter xp fine, but something goes wrong the programs don't save their setting to their foreign folder, they try to save it at the right path but wrong harddisk (the one i installed widows 7 on)