Adding a New Hard Drive & Copying - Multi-Slave Dilema

Adding a New Secondary Hard Drive & Copying from the Old

I am not exactly what you would call an 'expert' when it comes to computer hardware, in fact, I'm no where near an expert.
What I'm trying to do is upgrade my secondary hard drive, from an old 5GB drive to a slightly newer 20GB hard drive, and copying most of the data from the old to the new. Both of the hard drives work on my computer, and I didn't need to format them. Please note that I also have my master hard drive, which contains my main OS (WinXP Home, SP2) and such.
The problem comes down to these two attempts:
A) I try to to make both the 5GB and 20GB drives slaves, keeping the master, where then I can goto the command prompt and execute "xcopy" (I'm not sure if I need "xcopy32", 'cause I don't think I need to copy system files). However, I don't have enough data connectors and power cords (whatever those things are you connect to the drives) to support three internal hard drives, so I tried taking the pin cable from my DVD drive, along with the power cable, and plugging it into my 5GB (since the 20GB is already in place in my computer), however it returns that I have a Disk I/O Error. Is that because that data cord is for CD/DVD drives only?
B) I try connecting only two hard drives (I tested it with the slave and master first just in case I was disappointed) and booting it with an MS-DOS boot-disk (created using the "Format" option when I right-click on the A: drive). It boots the disk, and I am able to use the command prompt, however I cannot access any of the other hard drives, only A:. I try "A:\> chdir C:\" and it tells me I have an incorrect hard drive specification, or something of that sort.
Is there something I am doing wrong? Is there something else I need to do?