People have been pointing to existing applications that are already fast enough, and external bottlenecks such as Internet connection speed, to question why computers need to be any faster. I've heard this argument periodically over the years--the business keeps reaching plateaus for a while, then advances again.

What's below the radar of most people is that operating systems continue to get more complex, especially Microsoft's. The next Windows, recently named "Vista", is going to suck up a lot of processor power with things like built-in search, and stronger security that requires programs running in the background to keep an eye on things. The new Internet Explorer 7 will have additional processor-hungry features like realtime RSS newsfeeds (and tabbed browsing; watch out, FireFox). The Windows user interface is going to get more compex and require even more processing power; it'll copy Macintosh OS features like translucent windows and "bulging" animated icons. The inexorable trend of bundling once-separate applications into the OS is also a significant source of bloat. The trend isn't limited to Microsoft, as the Mac OS continues to grow. Linux may tend to remain lean-and-mean as there isn't the same commercial motivation to lard up on the bells and whistles. But for all OSes it's safe to say that escalating security concerns are going to cause all OSes to grow as new security code is added.

Trust me, before too long a 3GHz PC is going to feel like a dog.