I/O is just short for input/output and refers to a device or program that transfers data. Some devices, like a keyboard are input only, some like a printer are output only, while some like optical drives are both...
If you're not having trouble, leave your settings right where they are now.
ASPI refers to access layers (or software drivers). These allow communication with your optical drives cd/dvd-roms/burners, etc. Fab does not use the ASPI layers and windows xp no longer provides ASPI, but now uses SPTI This doesn't mean that you don't have aspi installed. For eg., some of the nero apps use ASPI.
Since you're not having trouble, I believe the best advice is...
"If it ain't broke...don't fix it"!
Hope this helps.