I have exactly the same problem. I have an 80GB 5400rpm drive I'd like to put into my Samsung P28 laptop (replacing it's 4200rpm 30Gb drive) but the laptop won't recognise the 80Gb drive - strangely an older IBM laptop I have recognises it fine, I can also use it as a portable drive in an enclosure so I know it works!
I have it as auto detect in the bios, but I'm guessing it has to be something in there that's preventing it from being recognised.
Any helpon this would be much appreciated by me also!!!!