Then the windows firewall is good enough
Antivirus AVG or Avast (Avast seems to give less problems)
Super Antispyware is a good enough to back up Defender which is built into windows vista and will realtime scan for spyware.
Add SpywareBlaster as a blocker and something to filter the spam and he will be well protected.
The only problem is getting him to remember to update his protection on a regular basis.Although Defender and Avast will do it automatically.