If you do not have the latest version of Office 2010 you can still create some presentations that can be shared online. Unfortunately, it is not nearly as easy as it is in Office 2010. If you would like to post to a website like slideboom, watch the video on the PowerPoint 2010 page which shows the process. The real challenge is getting it to work on Youtube.
If you are set on using Youtube, I'd recommend doing the following:
Once you have the image files use Windows Movie Maker to create a video file and then you can upload it to Youtube. Here is a video demonstrating how to do this: