Adding Internal Hard drive, Not showing

I have a dead laptop, I believe it was the hard drive, anyway. I took the hard drive out, connected it to my Network computer, all looks well, I heard it spinning (Good sign?) and then I booted the computer, it didn't actually load windows 7, it spent like a good 10-15mins saying "Loading windows 7" so I turned it off, moved the SATA cable to a different slot, it booted.. then when trying to detect the drive, it doesn't exist. Any ideas? I will need to format it, as it does have windows 7 on that drive aswell.
Kind regards,
Matthew

I'm confused.
What are you trying to accomplish? Fix the laptop, or just use the laptop's hard drive for additional storage?

If the latter, and you do not need any of the data on the drive, then you could use the Diskpart Utility to wipe the drive and/or format it, or a 3rd party program like Partition Wizard from the bootable CD.

But when you try to boot W7 on a different computer there will be problems because the W7 installation is tied to the hardware. And if the computer detects 2 bootable (Active) partitions then W7 may ignore the second partition or drive.

You could also unmark the partition as Active using Diskpart, if you are attempting to retrieve any data.
Partition - Mark as Inactive