DG's method is great for a business type machine - usually just the OS, an office suite, printer drivers and a few specialist oddments to reinstall.
However, a domestic machine will have a bucketfull of applications - mine does my home office, plus my photo handling plus my music collection, plus a load of other stuff that I use occasionally and always forget in a reload - there are about 4 folders on my desktop each with several applications, some of which (like the bank security) have to be remembered. Rather than one afternoon, its usually several day to get the lot back in....
Each unto their own, of course, and malcolmfrary has put his finger on one issue which will certainly cause problems for a rebuild - not having all the original software. I found this out some time ago,
and so all my systems have a folder labeled 'Master Software' where all the applications, drivers and other things to be loaded are copied first. Then I load the SW from this repository. This means I just need the master OS disks and that directory (which is, of course auto-backed up) to recreate any of my systems. The system I am sitting in front of at the moment has around 70 apps, and I am happy that, if it were to fail, I could build another in a morning with minimal work. I probably wouldn't put ALL the apps back, however...
For people like me who mainly use office type applications in the domestic context, (and not memory hungry stuff like video splicing), you don't actually need much computing power compared with what most people have available. Obviously this is more important to DG who appears to have a server farm in his loft, but this is a world away from most of the rest of us...
The reason I have lots of machines is that I tend to use separate systems for separate jobs - few of my individual systems are that powerful. For instance, I have several back-up systems for different purposes. The biggest multi-core ones are typically used by the kids for games and CAD/CFD. CFD takes all the mips you can give it, and I am looking into setting up a new farm just for this purpose. Office machines may be clocked at 2 ghz, with a couple of gig of ram. These are often the hand-downs from the old games systems, usually with a different graphics card! Network storage and backup machines may be P3s clocked at 1ghz or less. My web servers, for instance, are Compaq Deskpro SFFs - P3s at 750mhz, as is my Smoothwall firewall. Most of these 'service' machines run Linux and sit up in the loft where they just work, reliably and repetitively, for years on end.
