Tips to not get spyware:
1. Be careful what you install. Some "trustworthy" apps sometimes come bundled with it even though there's a checkmark to NOT install it. Often people don't pay attention.2. Use Firefox or Opera. After not turning anything up worse than a cookie on my system for over a year despite running AdAware and Spybot every couple weeks, I didn't even bother to install those two spyware checkers after my last format.
3. Coupled with the above, go to this site http://www.mvps.org/winhelp2002/hosts.htm do some reading and download the HOSTS file.
4. If you want, install Spyware Blaster as well. I don't any more for the same reason as Number 1.
Tips to not get viruses:
1. If something looks fishy, don't download it. I've followed this premise for years with e-mail and attachments and have never gotten a virus *knocks on wood*. I don't care how funny something purports to be, I don't open it.
2. Don't be stupid and open attachments from unknown people.
3. Be wary on warez/porn sites. Goes for Spyware too.
4. Get a good antivirus such as Kapersky, NOD, F-Secure or Symantec. Free- go with avast! or AVG.
5. Manually scan any file you download if you want to turn system monitoring off for fear it will slow down your computer.
6. Be very wary of the software you're using. You mentioned Limewire. Most of my idiot friends get viruses from using such apps. Be careful what you download and definitely scan EVERYTHING you do.
I'm sure there's more, but I'm sleepy and that's all I can think of off the top of my head.
Also, make sure to use a good firewall such as Outpost, Kappersky or Sygate.