need security program that doesn't take up too much space

[sofia]

Hello to all.
I just joined.  I am a senior lady, and self taught [such as it is], on the computer.  I would call myself familiar with computer, but certainly needing to know more. 
I do almost everything on my museum piece computer [runs windows xp prof], while my new one with windows 7 sits idle.  I totally prefer my old guy. 
This morning when I went to run my defrag program it informed me that I only have 10% of real space left.  Had no idea.  In past years I ran Malware bytes antimalware, but when they updated it it wouldn't load properly on my machine and I tried everything.  Tried over and over to work with their terribly bad customer service, which is by email only, to no avail.  Downloaded Avast and have been happy and virus free with it for a good while.  However have been concerned with the large amount of updates it puts on my computer daily, as I watch my space getting smaller and smaller.  Will have to do something for sure.  Can anyone suggest a good anti-virus/spyware program that is low on bytes, I guess you'd say?
Thanks
Sofia

[SuperDave]

Avast will only protect Windows XP for one year which is coming up quite soon. I would suggest Comodo.
Comodo Antivirus (Uncheck during installation "Install Comodo SafeSurf..", Make Comodo my default search provider" and "Make Comodo Search my homepage" if you choose this one)
It will install two other security programs which I uninstalled and kept Comodo.

[jason2074]

However have been concerned with the large amount of updates it puts on my computer daily, as I watch my space getting smaller and smaller.

This would also depend on what is the actual total storage capacity of your hard drive including unwanted programs installed and or media files that may be needing to be moved externally. Most users would complain of protection software system resources usage instead of the updates provided to protect your computer from new variants of virus or malware.