I've done this before and it works just fine, however, I found one thing very important.
The INSTANT that anyone comes to your house and sees your machine they will grab the joystick or press some buttons, thus turning your computer on. Now, it may not seem like a big deal, but it drove me nuts when people would just walk by with no intention of playing and tap a button.... then I had to go shut it all down.
I use a hidden power switch now for that reason.