When you're using your wireless network, it's a good idea to make sure nobody else is listening in.

To prevent that, WiFi (and its faster successors, 802.11a and 802.11g) can scramble your transmissions with WEP, short for Wired Equivalent Privacy. That should have been enough -- except that researchers soon found vulnerabilities that allow WEP to be easily defeated by an eavesdropper with the right software.

Developers of WiFi hardware returned to the lab and came up with a better system of encryption called WPA, for "WiFi Protected Access," which implements a much more robust system for securing an 802.11 network of any kind, a, b or g.

The problem is, there are now millions of WiFi devices already in use, all of which would need updates to benefit from WPA. What are WiFi vendors' plans to address this issue?

Apple won't talk about its plans for WPA updates, but it calls the new standard "a good thing" and suggests that, once it has been certified this summer, the company could easily provide downloadable updates for all of its AirPort products.

Belkin "endorses WPA enthusiastically," a spokeswoman said, and will ship new driver software for all of its WiFi equipment by this summer.

D-Link will support WPA in its "AirPlus" line of enhanced 802.11b products, plus its 802.11g and 802.11a/g hardware. WPA will appear in shipping products in mid- to late May and be available for download "soon thereafter," a spokesman said.

Users of D-Link's now-discontinued line of 802.11b hardware, however, may be out of luck: "There is a chance that we will not focus on upgrading that line of products," the spokesman said.

Linksys says it hopes to offer WPA support via downloads, "most likely in the coming weeks," a representative said. Adding the standard to shipping hardware will take some weeks longer. Some older Linksys equipment may not be upgradeable, but it's still testing to find out which models are ineligible.

Microsoft's line of WiFi access points and receivers, introduced last year, should have downloadable updates "in the near future."

Netgear says it will offer WPA updates for only some of its WiFi products. Its 802.11g and tri-mode 802.11a/b/g products should get a downloadable update in June or July. "The 802.11a and 802.11b lines of products will not be upgradeable to WPA," a spokeswoman said.

-- Rob Pegoraro