I need a helpdesk software solution which is easily manageable and provide self service. I would prefer to see a demonstration before I can make my decision.

Try Sysaid.
I have been using it for a couple of years and find it excellent.
Help Desk Software by Ilient

You can also try the HP ServiceCenter program. It's what we use at work and it's not too bad. You can learn more at the HP website.

Here are some great sites that compares and reviews different software packages. I used them when selecting one for a local non-profit:
Help Desk Software and Resources
Help desk software reviews with direct comparisons of different functions and price

Hey Kristi,
We have found Pathworks useful as a helpdesk solution at work. It's user friendly and easy to understand. It's also got self guided steps to help resolve problems easily. You may want to take a look at this video Pathworks - Using Pathworks. I hope this helps.