Exactly what is the difference between a master and a slave drive, whats it used for? How can I set one up? Also, as I understand it, a single device ata round cable is just for connecting one device to the motherboard such as a cdrom, fan controller, or hard drive? Whats the need for a dual device round cable, is that how you set master/slave drives? As far as the single device round cable goes, would you recommend the 10" or 18"? Finally, cards don't need round cables, right? Those plug directly into the PCI slots? Anything else I should know in this category?

each ide channel can handle two devices (unless otherwise stated by motherboard documentation). the master device on the ide channel is the one at the end of the cable (other end is plugged into motherboard). if you need to, you can install a second device on the cable(provided it's a two device cable). this device is called the slave. your main hard drive should be installed on the first IDE channel in the master position. the other devices don't really matter. when setting these devices up, you need to use the IDE HDD auto configure option in your BIOS. you also need to be sure that you have the jumpers on each drive configured properly. this info can usually be found on the drive itself, but you may need to consult the documentation for you drives. fan controllers do not plug into these cables the length of your cable is up to you, just make sure you buy shielded round cable. no cards use rounded cables to plug into the motherboard.

sorry, doesn't matter where drives are on the cable as long as their jumpers are set correctly.

pci cards have no cables, as you said. You are also correct in that dual device cables are only needed when you have a master/slave situation. Flat cables are easy because you can just get 18 inches and tuck away the excess under the motherboard or behind the drive bays. Round cables take a little more thought because they do not go where you want them too because they are stiff so you want to get the right length and avoid dual devices unless you need them. 10 inchers will probably work but you never know because it depends on where the ide ports are and the drives are. If possible you might buy two of each length and return the ones you don't use. Some people like the look of round cables. Some people like the fact that flat cables are easier to hide. Neither impede airflow if you are thoughtful. I prefer flat just because round gets somewhat in the way when I'm messing around inside the case. Most motherboards have three ports for external storage. One is a floppy port which is used for a floppy drive, and the other two are ide ports. The ide ports can be used for various types of drives, such as cd-roms and hard drives. Each port can have two drives on it, a master and a slave. The master and slave will both be properly detected by the motherboard as long as they are properly jumpered, something you have to figure out based on the particular drive's specs. The jumpers are on the back of the drive itself. All drives of all types ship from the manufacturer expecting that they will be the only drive on their ide port. For some drives this is known as master mode and for others its called single mode. So if you have one hard drive and one cd drive, just hook each up to a single device ide cable and plug it in and the motherboard will make it work. Its only when you have a third non-floppy drive that you need to worry about master/slave stuff. In that case you need to figure out the priority of each drive and have dual device ide cables available. Always put your boot drive by itself on an ide port if you can. Always make the least used drives the slaves. When building a system its good to print out a jpeg of the motherboard and draw out what will plug into each port. Thinking through the motherboard connectivity will save you the headache of not having a certain cable available.