Adapter and router problems

Hello,
please help me out!
so i received a free laptop from my cousin. he gave me a netgear 32 bit cardbus notebook adapter with the dell inspiron 4000. the netgear has an internet connection phone line in it. but the only way to use that line is to take the line from the cable box (which is on my main desktop computer) and connect it to my laptop. but then ill loose the internet connection on my desktop. so i do have a router. a wireless router, belkin model fsd6230-3. i bought a belkin adapter too. i used it for my internet connection on my old desktop. (i use to have two computers). i want to apply the router on the desktop and use the adapter on my laptop. but its been so long since i used it, that i don't have the CD anymore so i cant download new software. so then i decided ill just use the router and buy a belkin wireless card for the laptop. will that work? i dont know if my router will work because i don't have the CD to download it. or what are the new things i have to buy? the laptop is really old so there is no built in wireless.

but before when i applied the internet connection phone line into the netgear adapter which is in my laptop, it didn't work. the internet didn't work at all. so something is wrong either way