We're currently using Liberum, not fully started using it. However, the amount we've used so far and seeing the capabilities of what it is able to do, I think this is a great product considering it's free. It does everything we need for a helpdesk. It allows auto logon for the user (first time they log into the support, it'll ask for their forename, surname etc.)
The setup can be a little tricky depending how you want it set up. You can either use a SQL database (which we have in place), or you could use Access.
If you need any help to set it up just give me a shout.
Overall I think it's a good product, you may get better ones (especially if you're willing to pay). But does the trick for us.