I am a complete Linux newbie, but here's my experience if it helps:
I was able to get the D-Link DFE-690TXD Cardbus Adapter working on Red Hat 9, Kernel version 2.4.20-8 running on a Dell Latitude D-600 by selecting one of the "standard" ethernet controllers provided by the RedHat Network Config tool. When adding new hardware, I selected the adapter as a "RealTek RTL-8139, SMC EZ Card" and it worked. I did not try to compile the driver that D-Link offers on its site because it stated it was only good for 2.2.XX kernel versions, so can't speak to that. Don't know if this applies to RH7 but it might be worth a try.