Question about internet security.

[Duerig]

I recently moved. In my new apartment it is possible to pick up someone else's wireless internet. Since we are poor college students we decided not to pay for internet and just use the neighbor's network. My question is this: is it possible for this to be a security risk? My entire (meager) bankroll is online and I would hate to have to rebuild it. I have all the usual security on my laptop: Adaware, spybot, zonealarm etc, if that makes a difference. Any help / advice is appreciated.