1/2 day workshop

As part of my strengthening partnerships part of my VAD I have to create some sort of half day workshop next semester that deals with Internships, Volunteerism and Service-Learning. I have all these ideas of things I could do at a workshop but I'm not sure if they are appropriate or not. I have never run a workshop so I do have questions for anyone that has run one.
For example. do I have to stand up there and give a power point demonstration the whole time? Can I have guest speakers? Can I do individual and group activities?

Any ideas are welcome. Right now I'm starting from scratch and I have no idea how to go about doing this. If you have answers or ideas for activities, please let me know.

Nikki,
I think the important question is; what do you want them to take away from your workshop? Is it a volunteer training? Is it an informational presentation? That will help you narrow down your format options. Ultimately, some combination of the formats you suggested will probably be the best.

Whatever you decide the purpose is, almost nobody likes to sit still and be talked at for hours. Start off with a little ice breaker - if the group is large, have them break up into groups. If you want to be really tricky you could make an ice breaker that is relevant to the workshop. Ice breakers serve a couple of purposes: You get more comfortable with each other, you quickly feel like you've accomplished something, and you can easily use them to transition into the rest of your conference.

My program provides a five hour training workshop for our tutors. The format usually goes like this:
Staff introduce ourselves and the program
Tutors have an icebreaker
Staff presents material via powerpoint and lecture
Tutors process material via written reflections
Staff presents more material
Tutors process more material via guided conversations
Break
Guest speaker
Tutors engage in relevant activity/case studies
Conclusion

In this format, people get a lot of material but don't feel too overwhelmed. While we use it for our student tutors, I think the same logic applies to adults.
Hope this helps!