On the same subject, I have a fairly different (and some would say radical) opinion.
I believe the days of people individually renting/buying a rack full of servers and worrying about all the issues (as have been discussed above) are on their way out.
Cloud/Utility computing, where rather than renting the hardware, you just rent the computing power (and the related bandwidth etc) that you need, is the way forward.
I'm doing a talk at 'Datacentres Europe' next week in London on 'The disruptive case for utility computing' if anyone is attending. If not, I'd be happy to talk to anyone seperately about it.
For more info take a look at
http://www.nicholasgcarr.com/bigswitch/ by Nicholas Carr.