i have an MSI 850 Pro (MS-6339) Mainboard that's running an ATA 100 hard drive. my question is, if i add a ATA 133 HDD to run master to the ATA 100, will both drives default to 100? will a controller card enable 133 for the master and 100 for the slave? also, is there a big difference between ATA 133 and 100?