I've had problems with the automatic update not working all the time.
I have it set to hourly, but sometimes I'll go in and do a manual update, and it downloads 5 or more daily updates.
I've even waited till 10 minutes after the scheduled hourly update, and it is the same, so I don't think it is consistent.

I tired to run freshclam from the command line, but it failed with a clamd.conf file not found.
I found another version of clamav for windows that has not gui, but does have freshclam and clamd.
I was able to create a clamd.conf file that would work with clamwin freshclam.

These are the non-comment / blank lines.

DatabaseDirectory c:\docume~1\alluse~1\.clamwin\db
DatabaseMirror database.clamav.net
NotifyClamd c:\clamav\clamd.conf

The original file with the other clamav is called freshclam.conf, and has 113 lines.
I renamed it to clamd.conf and placed it in the clamwin/bin directory, and just changed the first line to point to the correct location.
The other lines were the only other non-comment lines. It does give an error about no notifying clamd, so perhaps commenting that third line.

So, not clear why the automatic updated doesn't seem to work, but the manual does.
I'm think of making a windows task or cron process to run freshclam for updates?