Rob...go to internet options, and clear out your cache.
Also, make sure you clear out your Recycle bin, and check that you havent accumulated too much on the desktop......your RAM will have to cope with all of this and it will slow things considerably. (particularly things like photos and stuff that we all tend to dump there for convenience and oftern forget to organise)
Next, check your HD out....scandisk it, and defragment.
Have you wound it up recently?