Any suggestions for optimizing screen captures for maximum clarity in a PDF brochure?

I've created a PDF brochure which incorporates client-supplied screen captures. Captures were created with SnagIt on Windows platform and saved as native Photoshop files. I adjusted the document size of each screen capture in PhotoshopCS (Mac) without resampling to avoid degrading the images, then imported into InDesignCS at 100%. For PDF generation, (print to postscript, then Distill in Distiller 6.0.1) I've turned off downsampling, hoping to avoid degrading the images.

The problem is, the client says the screen captures are fuzzy. I think this may be a matter of monitor display and zoom factor because when I zoom in on a screen capture in the PDF document it appears to be the same, pixel for pixel, as the original Photoshop image. But I'm wondering: Is there a better process or optimum resolution for creating screen captures for use in a PDF brochure?

Thanks for any enlightenment you can provide.

Natalie