Have you looked at all the stuff that is pre-loaded on many new PC's?  It's amazing how much trialware and other software is forced on your computer that you don't really need.  It is a good idea to take a few moments and remove whatever you don't/won't need. 

Dump the Quickbooks trial.  You probably won't be using that version anyway.  Also, look for such things as picture managers, Internet services and other links to software that you didn't order.  Many of these things will pre-load themselves into your memory also - which slows down your machine.