MadMark had a great answer, internal to your current situation is always the best way to get going. Make sure you get to know the guys outside your dept, and stop slacking your way around the helpdesk! I know in your downtime you game a little, surfa little more, and who knows what else... That's what surviving a helpdesk is all about, I've been there, and am glad I've been out of it for a few years now. Do a little more personal networking instead of sitting in your cube, and get noticed by others.
Getting to know guys in the upper depts is important, and setting up a career path development plan is very important. Only your boss has the connections to drop your name in various spots above your current reach, so make sure that he/sheis aware of your desires and they will find some small ways to help.
You're on a helpdesk? Where's all that surplus equipment that's not being utilized? talk to your manager about leading a "lab initiative" for the benefit of the other agents, giving you some vital experience and leadership capabilities. Share your knowledge by offering to run some training courses for the other agents on DNS, DHCP, NetMeeting, who knows... This shows your leadership and responsibility skills above the helpdesk and will lead to other opportunities and projects as well.
Brainstorm ideas about how you can improve your image so that people notice you as a leader. Helpdesk managers tend not to notice a lot of what their employees do because they're toobusy schmoozing with "their kind" to move up in their own ranks, so you have to do something similar in order to move yourself up too.
I hope this info is helpful at least, there's a lot of ideas to be taken there. Like MadMark said, be creative, there are lots of opportunities for you.
