cartoon or animation program?

[Emma Gilbride]

I have a PowerPoint presentation that would really needs a couple of 
slides with animated graphics. The graphics I have in mind are not 
complicated: a vat fills with liquid, the liquid changes color, the vat 
drains. I have checked PowerPoint and it do this on its own. Since I 
have never really paid attention to graphics/animation before, I don't 
even know what kind of software I need.

So, what (really cheap) software do I need to do this. Additionally, 
once inserted into the PowerPoint presentation, the cartoon/animation 
has to able to run on windoze afflicted machines.

Thanks for the help.

Emma