As above.
Zonealarm sucks.
If you want an AV with a low footprint then look at Kaspersky or Nod32/Eset.
Avast is about the best free one I can think of.
Here's a 3 month trial of NOD32 http://www.techmixer.com/free-3-month-eset-nod32-license-key-from-nod32club-china/
What they say does work, I did it myself.