Red Hat 7 is quite old. I don't know if it has built-in support for your network card. The DFE-530TX+ is quite common, I use one myself, so there is a good chance it may support it.
A module in linux is synonymous to a driver in Windows. My DFE-530TX+ uses the rtl8139 chipset to function. Unfortunately there are several variations of the card that uses different chipsets. If the kernel you are using does not have built-in support for your network card, you can try loading either tulip, via-rhine, or 8139too. My DFE-530TX+ uses the 8139too module.
First, test to see if your network card is already recognized
At the command line prompt, try entering
You may get something like this if it is recognized
eth0 Link encap:Ethernet HWaddr 00:0C:29:E9:A0:87
inet6 addr: fe80::20c:29ff:fee9:a087/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:202372 errors:0 dropped:0 overruns:0 frame:0
TX packets:168784 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:215486089 (205.5 MiB) TX bytes:15644789 (14.9 MiB)
Interrupt:18 Base address:0x1080
If you get an error message like
eth0: error fetching interface information: Device not found
Then you need to load a module to get support for your network card
Adding support for your network card
Red Hat provides a graphical utility to setup network cards. At the command prompt, type in
I haven't used Redhat in a long time, so I don't remember the steps. Hopefull you'll be able to figure it out on your own from the options given or the tips that Tinkster gave solved your problem already.
Here's a tutorial I found if you need it, covers Red Hat 7