If you are on broadband, I would recommend a Belkin modem/router.
It's easy to set up, Lifetime warrenty and free telephone support.
You will need a wireless card for desktop,.
Laptops are available with wireless access pre fitted.
For laptop purchase, it's worth looking at
I have used them many times and always had good after sales service and advice.
If you are on dial up.
Just get a USB modem and connect to laptop or desktop as required.
All te best.