If you're talking about the Crate Powerblock, I think it would go great with an amp modeler. I've even thought about getting one myself just to mess around with. I've got a POD 2.0 and a PODxt. Both work great in these types of applications. You just have to make sure that you turn off the cabinet and mic simulations, since you're actually playing through a real cabinet. In this type of situation, I prefer the POD 2.0 over the PODxt. The 2.0 has some extra warmth to it that sounds a bit more realistic playing through an amp and cab. The XT works great as well, but it sounds a little steril/digital through an amp and cab, in my opinion. But, when going straight to a computer or recording desk it sounds a bit better than the 2.0. Also, be sure that you run the POD's output, or whatever you get, into the effects return of the amp. This will bypass the amps preamp tone controls, so it will simply act like a power amp, and won't really color the tone of the modeler you use.

Use the search feature of the forum to do a search for these things. There are a lot of threads of various topics about amp modelers.