There are three ways to do this:
1) Plan ahead
If you use auto shapes with image fills, then the fills can be easily
swapped at any time without altering the animations. The downside is that a
lot of the picture tweak controls are not able to be used on this type of
image.
2) Use the add-in Animation carbon (15 day free demo).
This will allow you to copy an animation from a picture in your
presentation, delete the picture, insert a new picture then paste the
animation back onto the new picture. This is a very useful and handy tool
to have available.
http://skp.mvps.org/ac/index.html
3) Use HTML swapping
If you have the time to look thru the pile of little files made by HTML, you
can save the entire presentation as an HTML file. In the folder of HTML
content, your existing picture will appear with a new name (something like
slide0002_image002.jpg). If you replace this image with the new picture
(must be the same image file type) using the exact same name, it will be
replaced on the slide when you re-open it in PowerPoint and resave as a ppt
file. Note that any brightening contrast or cropping changes to the old
picture will be applied to the new picture as well. The animations will
also still be applied.

Signature
Bill Dilworth
A proud member of the Microsoft PPT MVP Team
Users helping fellow users.
http://billdilworth.mvps.org
-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
vestprog2@ Please read the PowerPoint FAQ pages.
yahoo. They answer most of our questions.
com www.pptfaq.com
.
>i am looking to change images, but each time i change an image all of the
> transitions disappear along with the original image. Can i retain all of
[quoted text clipped - 4 lines]
>
> thank you
Bill Dilworth - 31 Jul 2007 05:56 GMT
>>i am looking to change images, but each time i change an image all of the
>> transitions disappear along with the original image. Can i retain all of
[quoted text clipped - 4 lines]
>>
>> thank you
Oh, by the way, in the future, people will understand your meaning better if
you use...
Animations -- happen to things on a single slide
Transitions --- are how slides change from one to the next

Signature
Bill Dilworth
A proud member of the Microsoft PPT MVP Team
Users helping fellow users.
http://billdilworth.mvps.org
-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
vestprog2@ Please read the PowerPoint FAQ pages.
yahoo. They answer most of our questions.
com www.pptfaq.com
.
John Langhans [MSFT] - 31 Jul 2007 23:20 GMT
Hello,
| There are three ways to do this:
If you're using PowerPoint 2007 there's a 4th (and perhaps best) way to do
this.
* Use the "Change Picture ..." command.
Method 1: Right-Click on picture and choose the "Change Picture ..."
command
Method 2: Double-Click on the picture and choose "Change Picture"
tool from the Adjust group in the Picture Tools: Format ribbon tab.
Hope this helps.
John Langhans [MSFT]
Supportability Program Manager - PowerPoint