The router doesn't care what operating system you use -- the problem may be with the wireless adapter in your computer. Check the manufacturer's site for a Win7 driver for the wireless adapter.
Also, have you supplied the correct password and chosen the right wireless security protocol (WPA etc) for the adapter's user interface (or Windows' equivalent).
Suggest you try hooking the computer to router via an ethernet cable and disable wireless security and see if you can connect then (see router manual for how to address router's setup screens via your internet browser).
I am also facing the same problem after i upgraded my desktop pc and laptop from window vista home premium to window 7 home premium. But one of my other laptop using vista home basic don't have any problem connecting to internet using wireless G router.
By the way, my desktop (not using wireless) is hooked up the my router using ethernet cable, able to surf net after i upgraded to window 7 during the first 2 days. After that it became very lag, not stable, 90% have no internet access..... frustrated. And my window 7 laptop still have no internet access too.
Now I tried to bypass my router, which direct my ethernet cable to my modem without linking to my Wireless G routers. It worked very well for my Desktop PC, but not to my Window 7 Laptop. So I end up only can use my desktop for internet at home. Presently still testing the stability of my internet performance on my Desktop and still figuring how the solve the internet access for my two laptops.