using DLINK DSL-2640 to extend the signal?

Hello all,

I was wondering if anyone could help with the following :

I would like to extend the range of my wifi signal through the house. I CANNOT use a modem other than the one that was provided to me by my ISP, so I would like to use a router or wifi-extender.

I still have the DLINK DSL-2640 which I used to use.
- can I use it JUST to expand the strength of my wifi signal?
- if so, how do I configure it?

I am using all Mac's OS X 10.6.

Thank you for your help,

Alice in Italy