Popups
Well, since SP2 for windows was introduced it managed to avoid many of the annoying popup windows that sites spring.
IE7 will manage this much better, but until then it is recommended to use Google toolbar as one more shield in the way of popups.
Spyware
Norton AntiVirus handles spyware and worms as well as it does with virus threats.
Spybot Search and Destroy as well as Ad-Aware scan and alert against adware and spyware.
Microsoft Defender is another way to fight maleware.
Virus
Norton AntiVirus is the most popular anti-virus software.
Kaspersky is one of the more sophisticated anti-viruses, but requires more system resources.
McAfee is one of the oldest in the market.
AVG.