hi azaboo2:
to enter your system registry:
click "start" on the left bottom of your desktop
click "run"
type "registry" and type enter
It's dangerous for you to clear program keys which has already not useful.
you may backup your registry before you do this.
or you can download registry clean tools to clear your registry. It's safe I think.There may be many addresses to
download free registy clean tools. such as
http://www.digitalsupporttech.com/en-us/freetools.htm
beside this, to clean your program leftover files or folders
double click "my computer"
double click c disk
find C:\Program Files\XXX XXX means your removed program name
and delete it.
I hope these can help you.