Choosing th eright Hard Drive

My company running Dell Power Edge 1300 with Quantum Atlas V 18.4 ultra scsi 160 7200 RPM. the Dell server has ACI 7890 host adaptre. I need to add a seconed Hard Drive. If I install a faster hard drive(1000 RPM) with higher transfer rate, will thatcreate a problem? or will both hard drive will operate with the similler speed and rate transfer espacially the ACI-7890 can operate at 80 MB/second max transfer rate.