PCs are also designed with a mindset that saving $.10 on a component saves millions, encouraging overly cheap designs. Considering the typical PC customer has no problem with rebooting their machine several times a day, that gives them plenty of room to cut corners without pissing off their primary client base. This is not to say that you can't build solid hardware, but the typical PC vendors simply do not have a level of quality sufficient for 24x7 operation.
I doubt that anyone was suggesting building your backbone out of closeout specials from CompUSA. If you're reasonably careful in choosing and assembling your PC hardware, particularly in your choise of power supply and cooling, and run one of the mature BSDs on them, it's not hard to get 24x7 reliability. I have a bunch of BSDI boxes here doing everything from routing to DNS to web CGIs to X animations (often all on the same PC) and the number of crashes is down below one per year. If I rack mounted them and put them in a climate controlled environment rather than my spare bedroom, they'd do even better. As someone else noted, for what they cost you can get two of everything for hot sparing. There are vendors that specialize in BSD PCs who can put together systems like this for you. Even on cheapo PC hardware, the vast majority of the crashes using system software from suburban Seattle are due to software bugs, not hardware problems. My former main server which was rock solid under BSDI crashes daily with Windows 98. -- John R. Levine, IECC, POB 727, Trumansburg NY 14886 +1 607 387 6869 johnl@iecc.com, Village Trustee and Sewer Commissioner, http://iecc.com/johnl, Member, Provisional board, Coalition Against Unsolicited Commercial E-mail