I just ordered an arduino and usbtinyisp. My question is when loading the bootloader using the usbtinyisp, do you need to provide power to the arduino? Or can it bootload with just power to the usbtiny? Just trying to figure out how many usb cables I need to buy 
The USB-tiny will supply the power to the Arduino board, so only 1 USB cable will be needed at a time. 
There's a jumper on the board I purchased for the 5v.
...and the bootloader will already be burnt onto the chip!
But it'll be useful for later 