With an SM-57 and a GXL-3000, you've got a great start on your home studio. Two good but completely different mics, both sonically and physically.
The GXL-3000 is a large diaphragm condenser, with three (!) patterns. It's VERY sensitive (as are most condenser mics), and it can "hear" people walking around or TVs in other rooms, cars driving by, scratching your whiskers, licking your lips, fiddling with your cloths, fans, air conditioning, furnaces, light bulbs on dimmers, and lots of other things besides your voice and your instruments.
Have fun!