I'll add a vote for Reaper. I've used it off and on for a few months. If you're familiar with recording software in general already, it should be real easy to pick up, if not there might be a bit of a learning curve. But IMO, it is a pretty good software. I usually use Tracktion as my main host, but with their lack of support these days, I'm transitioning over gradually. The SM57 is an industry standard for micing guitar cabs, but it can be tricky to find the sweet spot. Another decent mic IMO around the same price is the Sennheiser e609. If you go up the ladder a bit, the Sennheiser MD421 or even the Royer R-121. take it a step further, and any combination of either would give you some excellent possibilities.