If space is a consern...
consider a dual purpose machine.
Like a showcase cab... where you can move the pedistal... and The rest is your entertainment system....
remember a whitebox / mame machine is a great combo... Tivo, DVD, Mp3, Arcade... great!
Next, a minipac machine is pretty small.
but cocktails are GREAT for small spaces... if you can use it for a cofee table. Another dual use... My wife wants me to get rid of my cabinet and make a cocktail table... but I have too many controllers and haven't come up with a good design for hotswapping on a cocktail table...