Whether u need a LAN card or not depends on the modem that u use with ur ADSL connection. D-Link DSL-502 T , as provided by MTNL can be connected to ur PC by both USB as well as LAN card...but LAN card is more stable than USB
when i connect using USB..it shows connected at 11Mbpsbut when i connect using LAN..it shows connected at 100Mbps...so i get mentally satisfied by seeing 100Mbps..therefore i connect using LAN>.hahabtw..both are same..u get same download speed in both..and both are stable..
Guys !!!!!!!! Pasting an article on EtherNet Vs USB.........It shud clear all doubts
There are two ways in which you can connect your computer to the DSL modem. One is Ethernet, which is a thicker networking cable with a large phone jack on each end. The other is USB, which is usually a smaller black cable with a flat metal piece on one end. Because there can sometimes be big differences in the performance and reliability of these two connections, we would like to share our information and suggestions on to our customers to help ensure an enjoyable and reliable internet connection. Please read below:
Ethernet has been around for at least 25 years as a communications standard for network connections. In order to implement an ethernet connection for your computer all you would need is an ethernet card installed in your computer, and an ethernet cable. These types of connections rarely have any issues with reliability, and has shown that it is a small amount faster at data transfer than USB. We highly recommend implementing ethernet as your method of connecting the DSL modem to your computer.
USB is short for Universal Serial Bus. It was created to be a universal way of connecting devices to the computer. Its great selling point was that it could communicate with nearly any device and the computer.
It quickly became an industry standard for web cameras, your mouse and keyboard, scanners, printers...etc. To implement USB for a connection on your computer to a device, the device must be able to use USB and you must have an available USB port on your computer. Almost every USB device will need drivers or software in order to actually be recognized by the computer and function correctly. However, the way in which USB communicates can make its connection very unreliable. They have made a new version of USB called USB 2.0, which is basically an upgrade in drivers. While this upgrade did handle speed issues, this did not help achieve any new progress with its known reliability issues.
So, as I previously said my vote is for EtherNet (LAN).
Well that is not universally true..atleast not in my case..i waz in U.K. last year and i used a 1 Mbps DSL connection with usb interface for a month and half...never had any problem...Maybe the D-Link modem has some specific issue that causes the USB connection to be unreliable...as there are plenty of USB modem's doin duty on DSL lines the world over...