Did the reinstall of Windows speed the system up at all?
Did you reinstall all the drivers for the laptop?
Beyond that you might go to PCPitSop and run the free, quick PC test and see if that isolates the problem. For one thing, it reports HD speed and for another also reviews drivers.http://www.pcpitstop.com/
Regarding your memory, is your computer slow just when multi-tasking or when on a single application?
How much memory do you have?
You can also run the free HD Tune software to check the health of your disk:http://www.hdtune.com/