I am running Chrome Tone with a Mac Book Pro that has a 2.2 Ghz Intel Core 2 Duo processor and 4 GB of RAM. I am running it in Pro Tools LE 7.4 and a Digi 002R audio interface. I haven't had a problem running it on this at all, however, I have only had a need for running one or two of these at once. Beyond this I don't know how well it would run, but since it is a big plug-in with a lot of parameters, running a bunch of them at once would probably slow your system a bit.
I've been using the McDSP Chrome Tone amp simulator for about six months. I have found it to be a useful tool not only for guitars but for all types of instruments. Since it has so many parameters, it is versatile and that makes it capable of a number of different uses. The price of this can't be beat, as I bought it in the Project Studio LE bundle for quite a cheap price. I would compare this to something like Line 6 Amp Farm or IK Multimedia Amplitube. While it is not as in depth as Amp Farm, it will cost you much less and it is probably a better comparison to Amplitube in terms of price and overall capabilities. For those looking for a plug-in of this nature, this is definitely worth a look.