I used to have the same issues for quite some time as far as latency. Each device will have it's own set latency and then software modeling increases that a bit. For me it did get better when switching to a semi monster rig from non monster rig. I'm using a quad core xeon 3ghz Mac Pro Tower with 8 GB of Ram. Even then it was still there til I upgraded to the newest version of the Macintosh operating system which makes more use of 64 Bit technology. So my DAW can address wads of ram, hit all four cores etc.
I've used two firewire interfaces and once USB. They were all really close on latency but this varies per unit. One thing to look out for is "Zero Latency Monitoring" on your next audio interface. This is a feature common to many consumer grade interfaces these days. But I feel your pain as latency used to just annoy me to death.
WORKAROUND
I started recording without any fx, just dry and applying the modeling after the fact. This is semi crap as the fx can impact what you play/how you play etc, and when it's just raw and dry the vibe is not there. It's a workaround though until you get another solution.
**That said, your work here is great and your tone is fantastic. If there is latency, I can't really hear it having any ill effect. Well done

Todd
QUOTE (Brandon Earman @ Mar 23 2011, 10:14 AM)

Maybe I'm asking for too much then as far as latency goes. I would just like to get it down to 7-8ms, but when I lower it to that, I get a bunch of "crackling" and it sounds terrible.