I have written a song in Guitar Pro, and now I want to record it.

I am thinking about getting a M-Audio USB Interface, and a SM57 microphone for recording the guitar (putting the mic in front of the amp), and a SM58 for the vocals.

Would this work fine, or should I only buy the SM57 and do the vocals through that one? Would it work better with a condenser microphone?

Any other suggestions, or any opinions on this?

Thx in advance..
Personally I'd grab an interface and a condenser.

Do the vocals with the condenser, and run the guitar direct in using VST amp sims to get your tone. Absolutely don't get an SM58 for vocals, total waste of money.