rock studio/lock-out

Hi, I am an engineering student at UCSB and my roommates band have a practice room in the area. At the moment they have a huge drumset, two halfstack amps, and two large PA speakers against the back wall (the wall you see when you walk in the door). If you look left as you enter the door, which is on the right side of the room, there is a small computer desk with my PC on it. I have an Alesis usb audio interface and a small behringer mixer. How can I arrange the wiring in order to minimize the outside sound that is recorded onto my recordings? The interface came with Cubase SE and runs smoothly. I think I have some problamatic ground loops. Can this be solved with a clean power supply (we use the crappy wall outlets). Also should I shield my mixer from my computer and moniter? thanks Austin