I find Ccleaner very useful - a free download (for the basic version, which is fine) Just be careful when loading that you don't include Mcafee too. (Uncheck a box).
CCleaner - PC Optimization and Cleaning - Free Download
Unloads the the accumulated 'junk' - temp files etc., and good for add/remove programmes too.
Btw - Sky Demon is working OK for me with Firefox...