Atmega8 MLF or TQFP Surface Mount

I have a project I wish to do that is very restrictive with space. I was looking at using the surface mount packages of the Atmega8 but noticed that there are 4 extra pins. It seems there are some extra I/O. As long as I match up the pins that are actually used on the arduino, will it still work? And will I be able to access these extra pins using the Arduino 0007 IDE?

Thanks for any help you can provide.

If this will not work I will just have to use an 8 pin PIC or an ATtiny. But I want to avoid buying another programmer.

It looks like you gain an extra Vcc, GND, and a pair of ADC inputs, 6 and 7. You should attach the Vcc and GND to their power and although you could probably leave 6 and 7 floating you might want to tie them down if you aren't using them.

Maybe you want to use the Atmega168? That high density package is already used in the Arduino mini variant and its extra pins are known to the development environment. Twice the code space for pennies more per part.

I was considering that but it looks like the 168 will be a liitle too big. One of the SMT packages for the Atmega8 is only 6mm across. Probably 8 or 9mm when you include the pins. I need to fit the entire board into a paintball marker grip, which also houses a 9V battery, lage Cap, and solenoid. I only have enough room for a low profile 15mm*50mm board. I should probably use an ATtiny that has an internal oscillator.