A new generation of super-fast wireless networking gear is arriving in stores.

But don't buy anything just yet, some tech experts say.

Gear maker Linksys has launched its first products using a new kind of wireless Internet, or Wi-Fi, technology. Called 802.11n, the new Wi-Fi is almost twice as fast as the speediest older version. And it's designed for multiple data streams, which makes it easier to download music and stream a movie from the Internet at the same time.

Linksys is offering an antenna, or router, and a card that lets a PC pick up the wireless signal. But expect to see 802.11n in everything from personal digital assistants to cell phones, says Linksys Vice President Malachy Moynihan. (Linksys is owned by Cisco Systems.)

Rivals such as Netgear are also rushing 802.11n products to market. And that could be a problem, says Andrew Garcia, of eWeek Labs.

The reason: The technical guidelines for 802.11n products have not yet been finalized. They're still being developed by the Institute of Electrical and Electronics Engineers, a trade group. Linksys and other equipment-makers are using a draft version from the IEEE.

That means today's 802.11n products might not work with future ones. "It's not a good time to buy," Garcia says.

Linksys says it can't make guarantees, but it hopes a future software upgrade will make its product compatible.

As is common with most new technologies, there may also be other kinks in early products. When Garcia tested the Linksys system, transfer rates tumbled when there was an older Wi-Fi network nearby.

Consumers might also want to wait until other developing wireless technologies come to market, says analyst Brian O'Rourke at researcher In-Stat. The most notable is wireless USB, which promises even faster data transfer rates than 802.11n.

The two are designed for different things. Wi-Fi is best for connecting a computer to the Internet, while wireless USB is better for connecting a mouse or digital camera to a computer.

Still in some cases consumers may have a choice, such as the best way to link a printer and a laptop, O'Rourke says. To compare, consumers will have to wait until this summer, when the first wireless USB products are expected to hit the market.

It's unclear how the new offerings will affect Bluetooth, another older wireless networking technology. Bluetooth is best known as the technology behind wireless cell phone headsets. This year, more than 40 percent of the cell phones sold worldwide will have Bluetooth installed, O'Rourke says.

Bluetooth is downright pokey compared with 802.11n. But it uses much less power, which is important for devices that run off batteries.

O'Rourke thinks there may be a niche market for several kinds of wireless. "It's hard to say that any one technology will overwhelm," he says.

While many U.S. businesses already have some kind of wireless Internet, only about 48 percent of employees have access to it, a recent In-Stat survey says. In-Stat predicts that worldwide Wi-Fi service revenue alone will jump from $969 million in 2005 to $3.5 billion in 2009.