Right ill start from the beginning so you can get the whole story,

Built a new computer but was short on cash so i scavenged two old hard drives out of other computers (1x20gb and 1x40gb).

Soon ran out of space, they were running realy slow so after a while i saved up and got a new hard drive, purchased a Maxtor diamond 10 250gb SATA II HD from ebuyer.com.

Hard drive came a few days later and i arranged all of my files that i needed on to the 40gb hd that didnt have the windows installation on. Unplugged the hard drive with windows on and inserted my new hard drive and began the windows installation.

I installed windows etc, the computer loaded up fine, copied all the files i needed and formated the old hard drive and put it in a my server and install linux on it, so this hard drives now gone...

So now, i boot up the computer with just the 1 new hard drive in (the sata) and i get a boot disk error.

So out of curiosity i insert the old hard drive with windows xp already installed on. And the computer now loads up fine, so i left my computer like this for a while until today.

I downloaded the windows vista beta and tried to install it on my old hard drive and got an error during installation, but the hard drive has now been formatted.

So next i tried to boot up the computer normaly like usual, but it would not load up, the boot disk error occured again. So i installed XP on the old hard drive again and it will still not boot up of the new hard drive.

Im not sure if the hard drive is correctly configured in BioS or something but ive tried nearly everything i can think of,

So any help would be greatly appreciated as ive been going at this all day now.

Thanks

Can you verify that the drive itself is working fine on another computer?