Grey screen and Leopard DVD stuck in machine

Hi,
I was working on my macbook when it started running really slowly and in the end just freezed.
I managed to switch it back on and thought i should run onyx on it to find out what the problem is. Onyx said i should use my dvd to boot blablabla.
So I did, and the hard disc couldn't be repaired so it suggested i save all my stuff and reinstall the whole thing.
I switched the computer off and turned it back on without the leopard cd inside, hoping that i would get to save all my stuff on my external drive (i have most of it but i have some interviews i hadnt yet had a chance to save as i had only just put them on the mac). All i got is the grey screen with the wheel thing, waited 20 minutes which lead to nothing.
As that didn't work, I decided to switch it off and on again with the leopard dvd inside, same thing, only nom the grey installation bar comes up and loads to about 1/8th and then goes back to the start, loads to 1/8th again, and then disappears. But nothing happens after that, just the grey screen and the wheel.

I've tried cmd+s, cmd+ctrl+p+r, but this lead to nothing (also not too sure what i was doing).

I'd love to be able to save my stuff, but if i can't i'd at least love to be able to reboot and reinstall everything.

Thank you so much for your help !
Excuse my english, i'm french.

Oh, at least now i've managed to get the leopard dvd out

Put the Leopard DVD back in, reboot and immediately after the chimes hold down the 'C' button. Select language, and then go to Utilities in the Menu B ar, select Disk Utility and run Repair Disk and see what is reported.

If the hard drive is repairable at the current stage, this will do it without wiping the hard drive. If again youy get the hard drive cannot be repaired message you have a dead drive on your hands and need another hard drive.

Sadly the time to back up all your files onto an external drive was when everything was working smoothly.

Hi, i've just done that and it says i should try to save everything i can and then reinstall.
How do i save stuff when i can't actually boot my computer ?

Thanks for your reply