When an application is uninstalled, it almost always
leaves a pile of
detritus behind in the registry.
The better solution I've found for this (insert expletive here) problem,
is to use virtual pc (free from microsoft) and virtual HDs. You have a
windows just to use the net, another to use another thing, and so on. So
when the thing got bloated, you just erase the "virtual HD" and spawn
another copy. Very pratic.