Linksys connected--neighbor's connection?

I found that my "wireless" laptop is getting online now with an unsecured Linksys network that I haven't paid for. Could it be one of my neighbor's connections that I am able to use inside my
house. It is picking up a low signal strength but I was able to get through with my IE Browser and
able to send emails and go to internet sites. I had 36mps.

If I have virus protection and spyware programs, is my laptop protected or vulnerable by using this
connection?