Hello and welcome to PC Help Forum.
Did this slowness start when you installed the new AVG 8?As I had to uninstall it a few people are experiencing AVG hogging or keeping there
CPU stuck at 100%.
I have dual core and this should not of been the case with 4 gig
RAM fitted.
You could do our prework just to be safe on the virus check?Its the prework link below in pink.