Input/output error after replacing Hard Drive

Hi there,

I've just replaced the hard drive in my Mac and am having problems installing the original software (OS 10.5, Leopard).

It's a MacBook Pro 13" Mid 2009. After it failed to boot up past the grey screen, I took it to the Genius bar at my local Apple store, and the guy told me the hard drive had definitely died. Thank god I'd done a Time Machine back-up recently!

I did a bit of research, (I'm not very knowlagable about computers), and eventually chose a Crucial m4 SSD, 256GB, 2.5" SATA 6Gb/s to replace it with. Crucial claim this is definitely compatable. All seemed fine as I put it in, but when I came to install the OS, I got a bit stuck...

There was no 'destination' to install to, so I went to Disk Utility. The new hard drive shows up, but there is no option to "Repair Disk" under First Aid (it's greyed out) and when I tried to erase and re-format the hard drive - I selected Mac OS Extended (Journaled) - it comes up with an error message: "Disk Erase failed with the error: Input/output error"

I've Googled the heck out of this, and although others have been asking similar questions, I still can't make sense of it all. Am I missing something obvious?

If anyone has any pointers that would be so great.

Thanks in advance guys :)