spyware spamwear from hades

I am repeatedly bombarded with a “Spyware Alert:
Security alert” that states windows has detected
an internet attack and “someone” is trying infectt my computer with win.3.Netsky worm. I immediately ran AD-Ware 2007 and downloaded MS Malicious removal tool. the worm is gone and I continue getting this spyware alert and a small orange flashing website come-on from ultimate defender and scanner adware remover program on the windows bottom taskbar. I have no virus software. Iam using windows firewall and use a router. Can I resolve the issue by using aregistry cleaner or will I have to get a virus protection software?