From that site, the one you selected will work fine, and you can probably just use it in place of the other modem, as it adds the wireless capability to what you have now.
There is no 3G connectivity in the place i live and if i want to browse net from my phone i have to use GPRS/EDGE.. It take years to load a page.. So the wifi is my only help.. I am going to buy that tomorrow. Thank you for helping me.. Really appreciate that..