PC trooubles connecting to Airport

I recently purchased a Macbook Pro and Airport Extreme. Everything works great on my end, but my wife's PC is having trouble connecting to the network. The HP laptop PC is extremely slow to connect and I usually need to plug in a network cable to restore the connection. After that is done then things work fine. Occasionally, she will be kicked off of the network or her she will load webpages at a much slower rate then our linkys.

I wish I could get more specific, but I am not that competent with PC or Mac.

Thanks for your help.
RL