I've been using the now out of date version of AVG on my network for about a year and it is great. We've been 'attacked' by viruses many times but AVG has always caught them immediately.
I found it quite difficult to set up - the company is Czeck (I think), and the instructions were not very easy to follow as I think they lost a bit in translation. Once it was running it was no problem to administrate, and they were helpful in support by e-mail.
I'm considering the upgrade to the new version, but as the current version is working fine I'm in no hurry.
From what I've read, I think some of the main improvements are in making it easier to set up.
I've found AVG a much better alternative to Norton/McAfee - not just cheaper, but my past experience of the others is that they can cause problems with other applications/operations on the PC.