A good practice when uninstalling apps is to, when you are in Manage Applications and click on the app you want to uninstall, if it is running select "Force Stop", select "Clear Cache" (if any), "Clear Data" (this will delete the apps corresponding folder in the /data/app folder), then select "Uninstall". That should give you a clean uninstall of the app.
Unlike Windows programs they don't install various components spread around a hundred different locations.