Agree with the internal blowing \ sucking of dust
Back up all essenstial data to disk \ drives
Format and re-install OS....... you will be suprised at all the 'stuff' you collect, think that its the best thing since sliced bread and then forget about it, a fresh system is IMHO, like clean bedding ( a pleasure to climb into )
EDIT:- good point GC, make sure all cards and cable's are secure
