MS LiveMeeting works very well (better than other similar products I have used in the past few years). I have used it a lot lately. If the money is an issue though, just make your Powerpoint presentation as remedial as possible, and be sure to include a page number on every slide so you can have your audience page through as you cue them to click. I have done this before many times too. Only problem with this (and paper presentations for that matter), is folks will click/page ahead of you and end up messing up your timing and flow. (I hate it when folks page ahead of me in paper supplied presentations, hence I never print out a presentation. I will email them the presentation later if they want it. If they want to take notes, tell them to bring a tablet and a pen.)
With MS LM, you set the pace, and you can share out a white-board, and other applications on your desktop. You can pass control over to other folks as well when you choose, and you can be asked and answer questions via an IM looking tool on/during the presentation.
(Doing a MS LM presentation as I type this actually.)