Are we talking 1.5 mbps or 1.5 MB/s ? My wireless setup is G-config using an airport xpress on the HUB, and I get around 1.5 MB/s - which is fine for streaming most videos, except for high-bit-rate HD probably (havent tried)
Devices that work are not always on the list. It all depends on what chipset is in the adaptor. All that WD are saying is that they have checked the ones on the list and found them to work.