Somewhere, Edsger Dijkstra is smiling:

From a Saturday WSJ article on Windows Vista (subscription required, alas):

Old-school computer science called for methodical coding practices to ensure that the large computers used by banks, governments and scientists wouldn't break. But as personal computers took off in the 1980s, companies like Microsoft didn't have time for that. PC users wanted cool and useful features quickly. They tolerated -- or didn't notice -- the bugs riddling the software. Problems could always be patched over. With each patch and enhancement, it became harder to strap new features onto the software since new code could affect everything else in unpredictable ways.

The UNIX philosophy makes sense:

A newcomer to the Windows group, Mr. Srivastava had his team draw up a map of how Windows' pieces fit together. It was 8 feet tall and 11 feet wide and looked like a haphazard train map with hundreds of tracks crisscrossing each other.

That was just the opposite of how Microsoft's new rivals worked. Google and others developed test versions of software and shipped them over the Internet. The best of the programs from rivals were like Lego blocks -- they had a single function and were designed to be connected onto a larger whole. Google and even Microsoft's own MSN online unit could quickly respond to changes in the way people used their PCs and the Web by adding incremental improvements.