This is something that doesn't have a correct answer. Everyone has their opinion on the matter. Personally, I use Norton AntiVirus. That's not to say I love it. It works well... most of the time. I've used McAfee in the past and have been very satisfied with it. I guess I would have to recommend one of those two.
I've had bad luck with Norton, it actualy could not cure some of the spyware it identified.
Norton Antivirus is not a Spyware remover. Antivirus programs handle viruses. Antispyware programs handle spyware. Antivirus programs may be able to identify some spyware, but they don't typically have the tools to remove them since they are tailored to remove viruses. If you want spyware removers, I can recommend some very good tools that are free.
Go ahead, please
My top recommendation would be Microsoft Antispyware. This program is good to keep running at all times. It is very good at finding spyware and other malware that is trying to install itself. It also asks whether or not something should be allowed to startup automatically and alerts you of programs trying to change internet settings (trying to hijack your browser).
My next recommendation would be Spybot - Search and Destroy. This program used to be my top pick, but Microsoft Antispyware is better. Spybot has also been getting worse lately IMO. I'd use this as a tool to use if something slips by Microsoft Antispyware. Note: don't install any of the extra tools that Spybot comes with, they are annoying at their best and worthless at their worst.
Ad-Aware is another program I use if my first line of defense fails. I only use it as part of a full line of scans to get rid of tough malware.
To get more assistance, I recommend reading Optimize XP. This guide is very helpful in that it provides information about many tools to help keep your system clean and that it offers many tips on securing your system against future infections. I couldn't recommend this guide enough.
I would recommend PC-Cillin 2005..I am using it from the past 1 year and it helped me alot by keeping me away from every kind of viruses. But the thing is if you update is on a regular basis.
My answer refers to current antivirus software. To efficiently protect your computer against viruses and other malware you need 1 antivirus + 1 firewall + 1 or more malware blocker.
This combination is very efficient and is recommended to anyone:
Microsoft Security Essentials + Comodo firewall + Malwarebytes.