I've bought a SATA 2 drive but i cant get i to work with my "SATA 1" motherboard, is SATA 300 backward compatible with SATA 150?

Yes, in theory they are backwards compatible but you need your board to be able to recognise it - I think it's called 'autonegotiation' from what I remember reading. You can also check on the hard-drive itself, one I've seen had a jumper to limit it to SATA1 speed. "I know that I'm mad, I've always been mad"

For example: Western Digital http://www.wdc.com/en/products/resources/DriveCompatibilityguide.asp SATA Compatibility Modes WD Caviar Hard Drive Labels are Key to Determining SATA Compatibility http://www.lifecomputers.co.il/uploadFiles/632680753562968750115.pdf Luke Chi

It is the auto negotiation it has to sort out.The manufacturers' Support showed me how to set the jumper. Got it to work :D Thanks anyway.

SATA 2 (SATA 300) is not backwards compatible with a SATA (SATA 150) controller. In order to use a SATA 2 drive on a SATA (SATA 1?) controller, the hard drive must have a jumper position to restrict it to using SATA (SATA 150), and a jumper must be installed. Some drives have the jumper position available (e.g. some recent Samsung), some don't (e.g. some recent Maxtor). This information can also probably be easily found on your hard drive manufacturer's web site. If your drive does not have the jumper position available, you must return it and get a SATA 2 one that does, or a SATA drive.