Mac Networking question....

Since recently being able to purchase a Mac myself after wanting one for some years, I was able to convince someone to bye a mac at work. Anyways, the problem he is running into is that he can't seem to let his iMac G5 keep a constant network connection with the windows XP computer and the printer.(That is he can get it connected, but the Mac after some time fails to keep connected to the network) Is there any advice out there for that? thanks in advance for the help.