The best way to get the tone you're after when miking up a cab, is to have a friend :) Get him (or her) to play your guitar in the same style as you, while you have some headphones on, and move the mic around until you get the sound you're after- don't worry about what is traditional, ie. off/on axis, just move it until you're happy- it could happen to be in front of the speaker, it could be 2 feet in front of the cab, it could be out to the side.... use your ears, not your eyes for miking :) As others have said, turn the gain down, and the mids up a bit (if you normally scoop), it'll stop that nasty fizzy tone that you get with lots of gain.
You may want to try using two mics to try and capture the sound- a 57 is a good starting point, but try and find a mic that has more mids/lows- the 57 is a fairly bright mic. Not saying that it has no lows, but pairing it with another mic can do wonders for your sound :)
And finally preamps- get a couple of decent ones, lower end mixers will have cheaper pre's, so get an outboard preamp, and run it line-in to the desk. Don't use EQ or compression on the way into the computer (or whatever you record to), apply it when you're mixing :)