The router's software was installed on our desktop years ago and now, the desktop is quite old and we have to sell it. I need to know if we need to reinstall the software again in probably in one of the laptops at home.

There is no software required by a router to be installed on a computer. What you had installed was crap supplied by the manufacturer that you don't really need.
To reconfigure the router you need to read the routers manual and everything can be done from your computer. No software needed.
Stuart
Thanks! I just thought I'll be needing it when I have to change the router settings. Just found out that I can do it without the software. :)
