1mb ISP LInk

I have a Netgear DG814 router/modem, 3com 10/100 NIC card in the desktop and
a Netgear WG602 WAP.

I have recently upgraded to a 1 mb link with my ISP. The speeds i Achieve
are the old .5mb. I have checked with my ISp and BT who say everything is in
order. It seemed to be the DG814, so I swapped for a new one, same problem.
This is mystifying as when I put my old alcatel speedtouch modem in I can
achieve the 1mb speed! It does not appear to be the NIC as my laptop
connecting to the WAP still only gets .5mb. Where do I go from here as no
one knows what the problem is.

Thanks

Phil