HP dv2615nr unable to find HDD

Hi, I recently started using my HP Pavilion DV2615nr again and so decided to upgrade from Vista to Windows 7.
I did a complete format and installed W7 Ultimate x86. Computer installed OS fine and was working great, until I let it update via Windows Update. First of all my optical drive wouldn't show up. So I tried to find a solution, nothing worked, not the regedit fix or anything else. I figured as I'd already wiped my machine I would just format the whole HDD and reinstall W7, this time ignoring any updates once it was completed. However, that wasn't to be.
The computer would no longer let me install anything, it wasn't reading my optical drive. Oh well, it's a 5 year old machine, the drive was bound to go eventually, and as I didn't need it I was too bothered when it came down to it. I hooked up an external drive and away I went, install started going fine, until I reached the "choose partition" page. "No drives were found." I installed a drivers disc I had lying around, still nothing.
In the BIOS menu there again is no HDD found. I've tried taking out the HDD, reinstalling it, I've also tried another HDD I had lying around, but again the same result.
I had an old XP and my original Vista installation discs at hand so I tried both of those, as someone suggested that it may be some "driver incompatibility" which I found doubtful anyway. Again, no HDD found.

I'm at a total loss now, what could it be? Motherboard issue? Wiped BIOS issue? Something else?

Any ideas would be gratefully received.

Thanks