There's a startup list - stuff gets an entry in the list and it gets pre-loaded at start time - it never lets smaller - the list - only bigger - find out how to deselect everything in your startup list - then run a free malware checking programme - I use Spybot but there are others.
Spybot warns me if anything is trying to get itself an entry in the list - gives me a chance to allow or deny.
Consider using Google Chrome as a browser - much quicker than others.
Get hold of CCleaner (free) and claen out the rubbish on a weekly basis - use its Registry tool once a year to clean the registry - defragment your disk annually.
