Before you move to a new card, hyave you tried to connect usng this card? How?
 
This is an onboard card, or PCI card?
 
There are good guides at the Ubuntu Wiki that may help.
 
Do you have a broadband connection, or DSL?

Thanks and sorry for the insufficient details.
It is a PCI card. No. I haven't tried these cards as yet. I'd like to check before I buy the card as I now have a Realtek 8139D card which works fine with Win XP and I am now connected to the internet through this card.
My connection is a broadband connection thru ADSL modem.
If Ubuntu does not detect, then I am back to square one. That is why I'd like to confirm before buying the D-link 520 TX or the 538 TX, the only two available with my dealer.
 
So--
 
 

Sorry for the typo, which mucked up my question.
 
What make and model card do you currently have?
 
What methods have you tried to connect to the internet?
 
When you say that the card is not detected, how do you know?
 
Again, look at the Ubuntu Wiki to see how to set up an internet conenction, depending on your type of connection.
 
Knowing what you have already tried to connect will help.
 
If you are new to Ubuntu, then realize that you need to configure Ubuntu for your type of internet connection.
 
For example, you probably set up your XP connection with the provider's CD. Since this does not work in Linux, you have to set it up manually and tell Linux what you have.
 
If you connect to your provider via dynamic DHCP, then this is quite easy.
 
If you provider uses a static IP address to allow you to connect, then you need some more information from your provider, or get it from Windows XP.
 
If you are an experienced user, then disregard what I have said.
 
If you move to a new card, you would still have to follow the same steps.
 
If you get to a terminal command line, as root user, then try typing in the command lspci -v. If the card is seen, then you will see some identification of the card in the output.
 
If you type in at the command line ifconfig and do not see a set of information for eth0, then you need to configure the connection for either DHCP (dynamic ip address) or static.
 

To answer your question about the other cards;
 
The D-link DFE-538TX is a realtek RTL8139 chipset and should work.
 
Note that it is shown on the Ubuntu Wiki card matrix as supported.
 
What is the full model number of the other card? usually it's somethng like DFE-520TX....I can't seem to find it.
 
Are you in the USA? Some of these cards are only supported outside the US. I looked on the D-link USA site for the 520.

Yes the card is DFE 520 TX. I just took a chance, went ahead and bought, installed and tred it out ! Voila ! Works like a breeze. I am online now and my os is Ubuntu 6.06.
 
I am really excited, amd even though I have been using computers for a long , long time, I am really thrilled that I am now a Linux User.
 
Thanks a lot.
 
Wish me happy Ubuntuing!
 
" I am, because all you guys are "
 
Thanks again !!