Unless you are placing the CDRW in the same channel of a HDD, use the cable provided. Using an ATA100 cable would bring no improvement to the CDRW reading or writing speed.
Assuming you have one HDD and one CD (or DVD), I would advise to put the HDD alone in IDE1 (ATA100 cable), the CDRW as IDE2 Master and CD/DVD as IDE2 slave (in this you could use the ATA33 cable). Unless, of course, you spend all your life making CD to CD "backups".