Why does my Linksys WUSB-G adapter max out at 23 Mbps?

Are you measuring this by doing a large download repeatedly at different times of day and timing them ?

Or are you just reading the speeds reported by the hardware -- which is usually unreliable.

Further, you should appreciate that wireless is duplex -- so the best you can hope for is about half the speed of ethernet.

I use my usenet reader (newsbin Pro 5 64 bit) to measure, which is fairly accurate.
My neighbour get the full 60 Mbps wireless with a N-router and N-USB adapter.

I have flashed the latest firmware for my router, there is a line of sight between the adapter and the router and the distance is approx. 8 m (25 ft).
Router is using a mixed mode, 20 Mhz separation on Channel 6.

Thanx for the reply.
I guess I need a N-adapter.

I don't think I'd get too excited about N wireless -- not least because the actual internet feed can vary in speed wildly depending on demand locally and globally.

But if you decide to go that way, I think the advice is still to buy router and adapter of the same brand to avoid possible conflicts.