It depends. If you get SATA, you need to make sure you actually have a SATA port on your motherboard. Only the boards that came out in the last 4-6 months or so even really have them. If you have the available ports, I do believe you can use both SATA and IDE...I'm not really sure.
But, if you are going IDE, I would suggest getting a Western Digital Special Edition drives. Thats all I will run anymore
I'm rather interested in trying out the new Barracuda (SATA) drives...cheaper than SCSI with the same speeds