Since you already found a frame, next should come fork, and then wheels. I believe JensonUSA has the Marathon S for 275, which is an excellent fork for the money. Wheels, Im not sure, but Ill bet phantomcow will chime in and help you out. As for drivetrain, I highly recommend SRAM. Maybe an X.7 set. Your best bet for alot of parts will probably be ebay for stuff like cranks and a stem.