No it's not a daft question. I sometimes get confused over it. ;-)
I think you have slightly mixed up your figures. You probably mean you have upgraded from 512Kbps to 1000Kbps ( 1Mb). Unfortunately no one has a broadband connection of 500Mbps or 1000Mbps, yet.:-)
So you have probably gone from 1/2 a meg to 1 meg. The 54Mb of the wireless connection suggests you have "g" standard, a very fast standard and will be fine with 1 meg broadband.
It can sometimes be very difficult differentiating between kbp and mbps and setting the maximum transfer rates of lan and wifi cards, makes a complicated situation even worse.