Backing up wth a mac book pro

I recently bought a mac book pro. I used to back up stuff from my white macbook onto an external harddrive but find the connections wont work with the macbook pro. Is there a lead i can get, or should i buy a new external hard drive?

Not enough info to provide any help.

There would be no difference connecting an external to a MB or MBP.

What do you mean it won't work? It doesn't pop up on the desktop, Finder doesn't see it, Disk Utility doesn't see it... What external is it and how are you connecting it... What version OS X are you using? How old is the external... When was the last time you used it?

The external harddrive is a Formac. What i mean is the plug on the end of the lead of the hard drive wont fit into the MacBook Pro socket. Its a different size socket. It used to work fine with my old white Mac Book, but with the Pro, the size of the socket is different.

Am making the only rational assumption I can come up with based on the limited info.

The white MBs had a FW400 connector while the MBPs have a FW800 connector. If your drive is using a FW then you need a 400 to 800 adapter similar to this. I would recommend reading the review there by Tim Thompson and go with an adapter cable instead of the regular adapter.

This is assuming I have made the correct assumption.

Thanks. I'll try that.