how do I get rid of unused file ext. and crap left behind after uninstalling programs and applications???

Personally, I recommend the Ccleaner programme. It`ll get rid of a lot of useless crap off of your system.

Download the Ccleaner programme from HERE.

During the following procedure you will be asked if you want to backup your registry. I recommend that you do so, then if you have any problems, you can restore the backup.

Run the programme and make sure all the boxes are ticked under the Windows and Applications tabs. Click the run cleaner button with no browsers open. Do this several times. Click on issues, then the scan for issues button. Click the fix selected issues button, followed by the fix all selected issues button. Do this several times, until no more issues are found.

Regards Howard