As some have stated if you want a free PowerPoint replacement look to Open Office. You can take PowerPoint presentations as input or even output in PPT format. When converting a PPT pay close attention to the fonts even font size sometimes it makes mistakes in this area.
As to making presentations more interesting in my opinion that is the job of the presenter. No matter how many bells and whistles or animations transitions you use, it will make no difference if you do not present the material well.
Another thing to watch out for is if you work for a company that has Branding police make sure your software is compatible with their Master. In many organizations there is a mandate to the background of slides (think corporate color) and possible the layout at the top (maybe the company logo). All of this must be able to transition to your new approach.
And one last thing make sure you can deliver a electronic copy that whoever you just presented to can open, we usually create a PDF version since our slides have notes.