This article from PCWorld reports that the WPA encryption standard used by advanced WiFi users has been cracked. In fact, not only has it been cracked but it can be done in no more than 12 to 15 minutes. If true, and the article says at least some of the hack is already in the wild, you should immediately switch to WPA2.
Some older routers (and PCs) can be updated to run WPA2 but if yours can’t, I would recommend buying one that can. YMMV. Insert disclaimer here.