Dropped ibook, new hard drive, airport woes

[brobson]

I replaced my hard drive due to dropping my ibook (much thanks so this forum for saving me hundreds of dollars!)
Anyway, I now am experiencing airport problems. I threw away the preferences and downloaded istumbler and see that a neighbor is interferring like never before. (i am like a 37 and he's like 30 and sometimes knocks me off) I don't understand why it's happening now. I am upgrading software but wonder if there is any way to block this guy or if anyone has any other suggestions?
Thanks in advance
Brenda
PS I am using network interference

 

[laidbackliam]

you could password protect your network.

i did that on mine and our network became quite a bit faster.

 

[brobson]

you could password protect your network.

i did that on mine and our network became quite a bit faster.

Any idea how I do that?
I have Time warner cable and Linksay (spelling?) router