There is a version of McAfee that some OEMs have distributed with their servers, but as far as I know, that version is not available for purchase. (Antivirus software which isn't designed for use on Windows Home Server shouldn't be installed on your server, since there have been problems with normal server activity being seen by some products as suspicious, resulting in issues on your server as important files are quarantined by the AV software.)
Avast has a product specifically for Windows Home Server, as does fSecure. BitDefender claims that their free product is compatible as well. I use Avast personally.I'm not on the WHS team, I just post a lot. :)
I have not installed the supplied trial of MacAfee that came with my new HP MediaSmart. I have read that it buggs you to change your workstation AV to MacAfee which is not something that I intend to do. How important is AV on the server? I am using it only for back ups of our workstations and some media sharing not for remote access. I use Norton 2010 on the workstations. I have not always been a Norton fan but the last few years versions sem to be good, intuitive and light so I am happy with Norton for now buit they do not seem to have a WHS version. Other question, can MacAfee on WHS conflict with Norton on my Win 7 workstations? Any other suggestions? Thanks.