Norton has a tendency to use a bout 40-60% of your system resources... I wouldn't recommend it to anyone. Try using AVG, it's free and very effective http://free.grisoft.com
I used Linux for a while, but I just couldn't get used to it, so in my opinion: ccleaner spybot s & d adaware nod32
Ad-Aware and Spybot are great, I'd also reccomend a little program called Hijack This!, it's a little outdated but it's incredibly simple and uses up hardly any memory. I personally use Avast's on-access scanner, I just like having something running in the background at all times that scans every piece of data coming into my PC. I also used to use Trend Micro's online scanner, but I don't like it now that they've redesigned it.
My dad and I have a separate computer that we use a firewall and a server, and that checks everything on all 3 computers that we own. It is very handy and when used with Linux, it's the best thing against viruses.
*checks processes list* It has 5 different processes running at once (4 are system processes and one is under my username), but none of them are using up more than 13,000 K of memory (comparatively, Windows Explorer is using 16,000 and IE is using 51,000). 3 of the 5 are 1,000 or less.
I personally like spyware doctor just because to me it does speed up the computer ALOT... the only problem is that you haveta pay for membership unless you find ways around it...
Don't pay for spyware removers. Ad aware and spybot search&destroy are the best things for spy/malware and they're free.
antivirus: -norton security suite (firewall+antivirus, my top pick) -AVG -mccafee spyware: -spybot search and destroy (my top pick) -ad-aware