I've never had any luck with Norton products--especially on XP--and as such have stayed clear of them. It's also a resource hog; running a full scan with Norton AntiVirus brought a P4 2.8Ghz w/512MBs RAM to it's knees...
There's a good article titled, "Why you should ditch Norton AntiVirus" at:
http://reviews-zdnet.com.com/4520-7297_16-5554923.html
I've been testing Mcafee VirusScan 2005 (v9.0)--which does include adware/spyware detection--and so far it seems to do a good job.
I've also read a lot of positive reviews of Trend Micro's PC-cillin 2005 (which includes a firewall), although I've never tried it myself.
Many of these companies offer various security packages; some are stand-alone A/V tools, some include a firewall for free, some offer additional security at additional cost... you have to do a bit of homework to find what you're looking for.
ZDNet has a comparison review of the "biggies":
- McAfee VirusScan Home 9.0
- Trend Micro PC-cillin Internet Security 2005
- Norton AntiVirus 2005
- F-Secure Internet Security 2005
The article can be found at:
http://reviews-zdnet.com.com/4520-3513_16-5553401.html
This may help you narrow down your choices.
Paul