Net security for netbook dilemma

My AAO currently has McAfee internet security on it. While I've had the netbook for a year I only recently started using it on the net. Anyway the 60 day trial is running out, I was happy with McAfee, seemed to start quickly and did not impede the netbook. The one year subscription is $90.

On my laptop I have Trend Micro and a license for 3 computers for it so I have already paid for 1 years worth (or 2, not sure which) for this program, and I can get a free pro upgrade too. Only thing is, I blame TM for slowing down the computer and adding several background programs in order to run. Not sure if this is justified as Windows XP install on this laptop is nearly 18 months old now. Benefit here is that I use software I own already and it is good software. The thing is, if TM is to blame for slowing down then I don't want to slowdown my netbook with the software.

The third option is to find a good free suite, like AVG and others to do the net security.

What do you think?