Slide shows on site = PHP, Powerpoint or other?

Hey! I'm the newest member, I think. Here's what I registered to ask.
I'm making my 2nd website and need to put some slide shows up. I've searched and experimented with Microsoft Powerpoint and it doesn't seem like it will work.

I need the slide shows to be controlled by the user. A picture will come up and when user clicks on it, the slideshow will move to next slide, etc. Totally interactive. I would consider using Adobe Flash/Actionscript 3 but would only get free trial because too expensive. Also need to change pictures often, so flash trial won't work.

The point is: I've heard PHP might be what I need to know, but I need the site up NOW and don't have time to learn. Is PHP what I need? Is it something else? Can I get the code somewhere?

I've read what i think are all the rules of this forum and hopefully did not break any. Sorry if i did, I'm running out of time here. This site is for the democraitc national convention here in Denver.

Thanks a lot! Chris

Here are some ready-made scripts...
Slideshow

Thanks a lot! This is just what we need!

No problem