Can I put a Prism graph into Word (or PowerPoint), then double-click on the graph to return to Prism for editing?

You can do this with Prism (version 3 or later for Windows only). Simply copy/paste, starting from the graph or layout sheet in Prism. You'll not only paste a picture of the graph into Word, but also embed a copy of the data, results, and settings required to create the graph. When you double-click on the graph in Word, you'll open this embedded object in Prism for editing. Changes you made will be saved in the Word file, but will not affect the original Prism file. If you prefer to paste a link to the original file, use the "Paste Special" selection on Word's "Edit" menu, and choose "Paste Link" in the resulting dialog box. Then when you double-click on a graph within Word, you'll open the original file within Prism.

Unfortunately, when you paste from Prism 4 or 5 to PowerPoint 2007,  the PowerPoint default is to paste a picture instead of a linked or embedded object (It works fine with Word 2007). But there are work arounds for the PowerPoint problem.