what should I do on wireless

I just bought a wireless pci card and plan to subscribe a broadband, but I found once I installed the card, I am already online, and there is a wireless access already. I don't konw if it is a hotspot or someone else wireless router. What should I do? just take it for granted or disable it everytime I turn on the computer and chose my new ISP service?

I didn't do any configuration on my coumputer to try to use other's network.