Folder with question mark flashing problem

Hello

I found a few sites showing the stated problem and did all the tests I found (to no avail) and also rang Apple care who told me it is the hard drive has died.

I took my macbook to the Apple store and unfortunately missed my appointment time but explained my problem and that I have had it tested in another Apple retailer and that the problem has been confirmed by Apple Care, so they were happy to replace my hard drive but (stupidly on my behalf) did not test it there and then.

All excited about having my little Mac back better than ever (and a full memory capacity for the new Football Manager) I made my way back home (an hours train journey away) only to find I have exactly the same problem and when I go to install the setup disks, it still doesn't recognise a hard drive to install to!?

Can anyone advise what the problem may now be and how it can be remedied?

Many thanks in advance,

Ciaran