I recently reinstalled my system from scratch (Windows 2000) in the process of installing a new hard drive. Prior to that, my Norton Systemworks subscription had run out and I was looking for another tool that could help with anti-virus protection since current versions appear to have minimum system requirements beyond my wallet capabilities and current computing power. After stumbling upon a trojan program first, I eventually found aVast antivirus which seems to work pretty well. These days, it seems that no solution can really be a catch-all solution anymore, and while I have found aVast to be pretty darn good, Spybot s&d comes highly recommended by a number of sources. I'm not inclined to spend the money to upgrade Windows as I find 2000 to be the most stable Windows release yet, and my hardware probably won't support any newer versions of Windows which seems more interested in memory hogging than feature producing if I am to believe the reviews I have read.

So, onto my questions: Is it possible to install too much anti-virus/anti-spyware/anti-whatever software on your computer? I do realize that each piece of software requires some computing resources, so there is a performance hit no matter what I do, but should I be concerned about limiting that by not having too many such software packages on my computer? Are there any known incompatibilities between s&d and any of the several commercial and/or freeware software packages out there which aim to allow for safer computing? The only thing I am currently using is aVast Antivirus.

Any thoughts or suggestions would be greatly appreciated.