Crop the picture after you copy it to the other slide.
http://office.microsoft.com/en-us/powerpoint/HA101326601033.aspx#2

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Thanks,
Glenna Shaw
Microsoft PowerPoint MVP Team
http://www.pptmagic.com
> Windows Vista now has a Snipping Tool in accessories to snip just a portion
> of whatever is displaying on your screen, but I want to know how to do the
> same thing in PowerPoint. Is there a way to "snip" a portion of a picture
> pasted onto a slide and then paste it onto another slide in the same
> presentation?