Cant say anything about trend micro as Ive never used it but Ive used KIS for the past 3 years and its been great. Great on protection. Im one to have a good backup and I use malwarebytes and superantispyware just to do occasional manual sweeps (dont ever try to run 2 av's at once.) On other Pc's I have tried the AVG free route and others, but when I did the weekly superantispyware or malwarebytes it would alwyas find tons of adware and others that AVG let through. So far Ive never been able to find anything with my 2 backup programs that my real time KIS let through. The bad thing about it is that it lowers system performance (at least on this pc it does, Ill have to see if I decide to put it on the rig I just ordered today) startup takes about 2-2.5 min on my current machine running vista with a core 2 duo 2.2 ghz and 3 gigs of ram. Windows performance says KIS is causing slow startup times and that it takes 67 sec for it to get it up and running. For the rig I purchased today (i5 750, 6gig 1333mhz, 500 gig seagate hd, blu ray, gt 240 1 gig, antec 300 and 650 psu w/win7) Im considering switching over to Vipre's antivirus/antispyware combo in combonation with pc tool firewall. Ive used the trial on this PC and it was ver quick and light on resources, and also had some nice additional features like seeing hidden programs running on your pc and a total file eraser where it not only deletes a chosen file but overwrites it with 1 and 0s (at least I think that was what it did. Im still on the fence about it though as I have had good experience with KIS. And before I get railed at for it I know the gt 240 isnt great but its all I really need as Im not a gamer and just needed something that would run HD video and had an hdmi out to run to my plasma.
* Im noticing other places that avira seems to also be good, but I dont know if it is a full suite and has a firewall or not.