Briefly:
a 2Ghz Mini vs a 2Ghz iMac, each w/ 2GB of RAM, are $1024 vs $1349, respectively. That’s $325 on the face of things, for a decent monitor (but a 20″ widescreen monitor can be had from Dell for a helluva lot less (the “Good” 20″ Widescreen is $269). And what else?
* A decent video card, for starters. The 950 supports OmniDazzle, for instance, and I assume the Dashboard water-droplet effect, but it’s not going to exactly light the room up with performance.
* 250GB Serial ATA vs a 160GB 5400 RPM laptop drive. Does anyone even ship a laptop with shitty 5400RPM drives?
* iMac is arguably expandable (at least a new HD and another stick of RAM, I think?)
* iMac comes with keyboard and mouse (about, what, $50?)
So when you diff it, the extras - a little bit better hard drive, a much better video card, some fit/finish, and a decent monitor - makes the iMac about the same value as the Mini.
Basically unless you already have a monitor that pwns, why bother with the Mini? (Conversely, get the iMac if you’re looking for a new monitor)