Yes, you can add a 7200rpm IDE drive as the slave drive. Just make sure your jumpers are set properly on both HDDs. Use with Master (on the original drive) and Slave (on the second drive) or Cable Select on both of them.
need bit more info...the master has ATA/100 interface with 2mb cache.what wud be my preference for the additional hd apart from 7200rpm ide. Can i have a larger cache memory for this or is it of no use. Is a ATA/100 interface must?