Windows has no problem addressing 24 drives: with the available drive letter addresses being 'C' to 'Z' [logical or physical], the limitation comes from the device type and interface
Most motherboards have 2 only IDE Device Adapters. On to each of these you can attached only 2 X IDE Disk Drives. Thus 4 drive limitation, including Optical disk drives
A single SCSCI adapter can have all 24 disk devices daisey chained
Some motherboards have 4 IDE Device Adapters. So check out what you have
Should you wish to add extra physical IDE drives, then check out the cost of a PCI comnpatible IDE Device Controller, so that you can use one of your expansion slots. Here's one which is available
