Wireless Network Question?

[Zedder]

We're going on vacation soon and the condo we have does not have internet service, However...when we were there last time, I turned on my laptop and a couple of wireless networks were within range. Is it OK to use these while we are down there or can someone access my computer while I am surfing or picking up email??? Sorry if this is a dumb question, but I don't use wireless at home and have no previous experience. Thanks in advance