Some helpful advice from Scott Kelby about using screen captures in print:
From Scott Kelby’s "Down and Dirty Tricks for Photoshop 6": "Screen captures are low resolution by default, but you see us using them here in this book, and you’ve seen them in magazines, books, software packaging, and a host of other places in print. So what’s the trick of getting enough resolution to go to press at 200line screen? It’s simplemake the screen captures much smaller when you import them into your page layout application (at least 50% smaller). That’s the whole trickshrink ’em. NOT in Photoshop, in your page layout application (if you try to shrink them in Photoshop, believe it or not, they’ll get fuzzy. Even if you reduce them just 5%, instant fuzz. You HAVE to do it in your page layout application)."
"There’s a color separation secret, too. Before you convert to CMYK, set your Black Generation to Maximum (in your custom CMYK preferences) to force the black type to appear only on the black plate. It works wonders."