Ok, my question is pretty straight foward, if a mother board has both Serial ATA and Parallel ATA, can you use them both? or is it limited to using one or the other?
Yes they both can be used. SATA is one drive per port, so the number of SATA drives you can have = number of SATA ports. PATA can have up to two drives per port.
To the best of my knowledge, they can both be used simultaneously.