Serial/USB is how to send the data to the PC and a different issue to decoding the switches.
I know, but I would connect the cables directly into the PC if i had enough ports.
Do you have access to two wires from each switch?
Nope, one wire is common (don't know if is correct to say this) for all the switches. I have acces to only one wire from each switch.
Nothing immediatey springs to mind except 30 shift registers Smiley but there's bound to be some keyboard decoder chips out there.
Maybe there's a simple way to "expand" the io ports in Arduino :D.
Thanks.