MR814v2 Rtouer Speed

I've been using the wireless router for about 3 months now and the
speeds just haven't been up to the standard I expected. I had a lot
of trouble configuring it initially but got over those problems by
upgrading firmware (now on 5.3.0.5). The problem now is that I try
bandwidth tests and get some very slow responses (Genarally the speed
of the internet is slow when using the wireless router all the
time...)

I tried this test - http://www.2wire.com/?p=154 and I got the
following results:

Ethernet Cable Broadband - avg 125 Kbps
Wireless Cable Broadband - avg 60 Kbps

This is less than half the speed acheived over ethernet cable but
still well below capacity.

Can someone explain to me if I am reading these results incorrectly or
if there is a genuine problem with my router.

Thanks

Shannon