What, specifically, is the position for? Networking? Helpdesk?
Some general hints:
Try to portray yourself a friendly, helpful, personable.. Um.. Person.
Emphasize that you have good communication skills and are able to easily explain technical concepts to others.
Try to show situations where you've taken on a challenge and achieved a goal, preferrably something to do with another related job, something that they can understand and see how you could do the same working for them.
Don't lie about your technical background, but don't be too self-effacing. If they ask if you understand a particular technology, be sure to indicate that you've had some experience in it (if you have!) and that, if you're not a guru, you feel confident (key - Confidence!!) that you can work you way through it, as necessary.
Talk about how you've participated in a team/group effort and hit any leadership you've had with teams. Don't try to make yourself out as a budding IT director, just as someone who can lead an effort, should it be a complex support case or a major deployment where you have expertise.
At the end of the interview, they will ask if you have any questions. Think some up ahead of time. Don't ask stuff like salary, benefits, etc. - The first interview isn't the time for that. You should ask about the technologies they have deployed, the team you'll be working with, what customers they serve, etc. Always make sure that you have a comple of questions and make it sound like you're prepared or are intelligent enough to pick some questions out of the first part of the interview.
Lastly, know the company you're interviewing with. Have a very good idea of what they do, look at their financials, read their web page and try to make sure they know that you've taken the time to do the research.
Good luck!
- G