Long Story short:
Had an 80gb drive, bought a 200gb to store extra stuff on, then an external 250gb to back up the storage one. The 200gb randomly dissapeared for a few weeks, then the 250gb started to play up. Got all that sorted and its been fine for 6 months, then started to play up again, then worked.
I bought another 200 gig external to save my music, photos etc which is running perfect, and took the 250gb out of the caddy and put it internally on an ide raid channel (only one i had left) and it works great.
Last sunday i switched pc on and the message "Couldnt detect hard disks" reared its ugly head, so after a while and some cable wiggling its all running smoothly again. I can send the dodgy drives RMA back to *cough Maxtor, as theyre still under warranty, but on checking my c:/ with hdd tune i found it to be running along at 4mb per second, should i send it back too
Bearing in mind then that i will have an empty machine until they are replaced 
Had an 80gb drive, bought a 200gb to store extra stuff on, then an external 250gb to back up the storage one. The 200gb randomly dissapeared for a few weeks, then the 250gb started to play up. Got all that sorted and its been fine for 6 months, then started to play up again, then worked.
I bought another 200 gig external to save my music, photos etc which is running perfect, and took the 250gb out of the caddy and put it internally on an ide raid channel (only one i had left) and it works great.
Last sunday i switched pc on and the message "Couldnt detect hard disks" reared its ugly head, so after a while and some cable wiggling its all running smoothly again. I can send the dodgy drives RMA back to *cough Maxtor, as theyre still under warranty, but on checking my c:/ with hdd tune i found it to be running along at 4mb per second, should i send it back too
Bearing in mind then that i will have an empty machine until they are replaced 
Might be worth downloading the Manufacturer's diagnostic software just to make sure it's not the drive (and have a good look at your cables - nothing more annoying than a dodgy cable!)