The Linksys WUSB54GC is avery good performer out of the box, thanks to a Ralink chipset and overall good design. It still has some limitations due to its internal antenna. With the addition of a good external antenna, it rises to excellence.
Note: If you can't find this wifi device, there are newer high power wireless adapters and routers available. Get a new one, and connect!
This project can greatly increase the throughput and range of the Linksys WUSB54GC. It can also be applied to just about any commonly available wifi adapter or router; one simply cuts out the built in antenna and runs coaxial cable to a high gain replacement. I have seen throughput on a 30 meter path go from 5.5 MB/Sec to a solid 54 MB/Sec - with reduced interference and no need for amplification. Note that longer path lengths (more than 200 meters or through walls and vegetation) may require making this modification to a device higher powered than the WUSB54GC.
First, look at the circuit board. It boasts an efficient and clean layout. Data passes through a USB port on the left, and the antenna is etched on the right side. This modification is not difficult, but bright lighting and use of a magnifier is suggested due to the small surface mount parts and thin circuit traces on the adapter. The WUSB54GC presents a small work area, so use caution.
Note: This modification is quite similar to the one for the Belkin F5D7050. Look at that page, and become familiar with the general concepts of adding an external antenna to a router or USB wifi adapter.