I use AVG and it updates daily when I switch on can any explain why it seems to take forever to update?
If it's the same time(ish) every day, it could be that their servers are busy.
That's the main reason I switched to Avira.
I never seem to have a problem, try changing th time of the update as Katzy has suggested.
The updates are sometimes just definition files and sometimes it updates the program too. Obviously program updates are considerably bigger so will take a while to download and install.