One computer I have is running Windows XP, and is connected to the internet wirelessly, connecting to router A. I intend to share said internet connection with my second computer, running Kubuntu 5.04 (No, I cannot do this the other way around) through a second wireless router (Being used as a normal router, I don't have an only wired one) . I believe that I have set up internet connection sharing properly, but when I try to connect on my Linux machine, I get only a few B/s, and cannot do anything whatsoever without it timing out. What should I do?

That went over my head, could you explain again, slowly and in steps, please?