If it slows down again shortly after you restore the notebook, then that suggests it is due to something you are doing.
Note you MUST have a good anti-malware solution and a software based firewall running. There are several capable anti-malware solutions - I use MSE and I use Windows Firewall. After that, it is up to the user to "practice safe computing" by keeping the system updated, patched, scanned and blocked - and to avoid risky behavior like filesharing via torrents or through P2P sites that allow illegal filesharing.
And it is slow at everything, or just surfing the net, or something else?