When you're a falling giant, you'll grab anyone's hand for help, even a rival's. XM just demonstrated that in pairing with Sirius. Why shouldn't Microsoft follow suit and hook up with Yahoo! to combat their common conqueror? Google has dominated both in the booming market for search advertising online, and now Google is taking on Microsoft in software as well, offering businesses a cheap suite of programs to handle e-mail, word processing and spreadsheets. What's in it for Yahoo!? Microsoft's marketing muscle, combined with its customer reach, would put Yahoo!'s newly polished Panama advertising platform in front of millions of corporate decision makers and small businesses around the world.