USB is the only way to go.
The maximum spec of IDE is 18 inches. Two-foot IDE cables are pretty common, despite being longer than spec.
Im debating wheather to extend my IDE cadle for CD/DVD dive or just go wit a USB CD/DVD Drivce cause the PC will be in the trunk but i want the dvd /cd drive in front for easy access. I am do know in IDE cales over 36" the data degradation. What has any one ever had to make this decision.
If you already have a IDE drive, you can use a IDE to USB adapter..
im going to be putting my drive in front of car for easy access as well. Only thing i would say is go with a slot load slimline drive. its tough to find a good spot in the dash whera a NON-slot load's tray can pop out and have no chance of getting damaged, broken, snapped off. im either going to put mine ontop of monitor thats gonna be fabbed in the dash or have mine slanted down at an angle where the front asghtray goes.