Is AVG 7.5 FREE EDT enough for complete security?

Your choice with Eset's suite was a good one, their heuristics is the best in the industry and the resident scanning engine is fast with low resourcees and is also the top ranked AV product with Independent test labs for years. They also hold the record for most VB100% awards (44 and counting) and consecutive awards. Virus Bulletin's VB100% award is the industry standard and the most coveted award any AV product can attain.
I know many folks love AVG and lately they have actually been getting straight VB100% awards, but their recent history was rather spotty.

Actually, the most recent VB Comparative tests were the most comprehensive and the toughest in history with many polymorphic trip-ups, and a number of well known vendors Failed. Here's a list of the failures:
Agnitum Outpost Security Suite Pro
Ahnlab V3
Alwil avast
BitDefender AntiVirus 2008
Bullguard
Doctor Web Dr.Web
Hauri ViRobot
Ikarus Virus Utilities
K7 Total Security
McAfee VirusScan Enterprise
Norman Virus Control
PC Tools Antivirus
Quick Heal Anti-Virus Lite
Rising Antivirus
Security Coverage PC Live
Sophos Anti-Virus
Trend Micro Internet Security
VirusBuster Professional
Webroot Spysweeper with Antivirus
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All the other top vendors submitted for this test and passed so if your's is not listed it most likely got the VB100% award.

One thing that always makes me snicker is when I see folks extolling some garbage product's virtues by saying they've never had an infection while using it....well, if the product doesn't actually catch any problems, of course they'll never know about it... will they

I think Ad-Aware 2007 is pretty good I use it and Ad-Watch catches a lot of stuff

AVG 7.5 will no longer automatically update after May 31st. I can't complete a download of AVG 8 - I'm getting the errorOx800704C8 message I've seen discussed elsewhere (operationcannot be performed on a file with a user-mapped section open). Any ideas, please?

When I have to settup a new system with a free AV(I recomend NOD32) I use Avira or Avast.

AVG has slipped to much in the last year to be trust worthy anymore.

No, I had AVG 7.5 on all my systems until a nasty virus not only got through AVG but actually infected it too. I have since switched to Avast, which caught the same virus that AVG did not and switched all my systems over to Avast. I will never use nor recommend AVG to anyone ever again.