Hi Carl -
Currently the fastest fully-ratified standard is 802.11g. It is capable of a theoretical maximum throughput of 54Mbps. Of course, "theoretical maximum" might as well read "in-your-dreams maximum". In the field, I have run across many environments which are conducive to RF, and can give consistent speeds around 36Mbps.
There is a new standard currently being finalized by the IEEE. It is called 802.11n. It will supposedly be capable of increasing the effective range of WLANs considerably, while at the same time increasing throughput somewhere in the neighborhood of 120-200Mbps. Until the standard is finalized; no one really knows.
"G" devices will be available on the market for quite some time after the eventual release of "N" devices. I have implemented WLANs based on the 802.11g standard for years now. The throughput and coverage capabilities are sufficient for most applications, including VoIP over WiFi, streaming video, and mission critical applications (e.g. clinical devices in hospitals).
If you can wait what might be another year for all of the bugs to shake out; you could wait for 802.11n to come out. Otherwise, try 802.11g.
Hope this helps! If so, please rate.
