Avira Antivir Update
Avira have updated their Antivir to v9.0
There is still a free for private use edition, and it still works with Windows 2000.
My personal advice is that if you already have Antivir then uninstall the previous version before trying to update. The automatic uninstall and reinstall didn't work for me on XP SP3 or Win 2000 SP4.
Incidentally, if you need to do a reinstall, the registry may need to be cleared. Conventional registry cleaners won't do the job; you need this:
Get their own registry cleaner.
Runs in Windows 7 (build 7022), too.