It could actually overheat, depending on what else is in the cabinet and Temp and all that stuff. One way you could control it is just cut in a fan in the top of the cabinet with the airflow out and one on the back bottom with the airflow comming in. Just in case.
I second this. There's too many factors to say for sure; but I bet if you are pumping loud music though thi,s it will make some decent heat.
I also agree a top mounted fan and bottom mounted holes will probably take care of it as long as your interior isn't too crowded.
You might try just an 80mm case fan that you can power off most any 12 volt supply (PC, Jamma PS, etc). These usually work for me and don't draw much power (.8-1 amp, I think).
The key is lots of holes at the bottom.