where to get Ubuntu drivers for...

Did you check whether it works out of the box?
Just plug it in before booting your computer - ideally before installing, so the installer knows what drivers to install.
This is obviously just a guess, but usually hardware that's reasonably common and not too new (i.e. few months from market introduction) works pretty much automatic. For my current laptop (ubuntu 8.10/intrepid, on centrino 2 platform with external graphics that came out few months before), I didn't need to install any drivers by hand.

Only if it really doesn't work out of the box, then you should check on the ubuntu forums or on google, and you'll usually find tutorials how to do a hack (since usually people tried before you). But that's usually a last resort, and you can screw the nice fully automatic/integrated way your system behaves if you install things like drivers by hand (rather than using the installation tools that ubuntu provides). A google search "D-Link DWL - 120+ driver ubuntu" for your hardware gives quite a few links (dating from 2004-2006, so I'd guess it's out of the box now).