Slave drive VS primary hard drive

I have swapped out hard drives before. But what I want to do is buy a new computer and make my old hard drive the slave drive. Is there any documentation I can look at on the web, or is it easy to explain how to do this? Does it matter that one PC will be WIN98 and the other WIN95? Is it possible to crash the hard drive and if so what is the most recommended way to back up?

Thanks,

Rob