Vista 64 extremely slow internet

Hi everyone.

My machine has been running vista 64 for about a year now with no previous internet problems.

In the past it was connected to the internet through the ethernet port and a vpn and that worked great.

I've recently got fibre internet at home which works great and is super fast on all the other computers in the house. For some reason though it is unbeleivable slow on my vista 64 desktop. I get full wireless signal and the wireless connection never drops but most pages time out or load very very slowly, I get download speeds of 1-2kbs which always end up failing...

I thought it might be the wireless card (D-Link DWL-G510) but i've got the correct 64bit drivers and when I set up an ad-hoc connection with a laptop and shared it's internet connection it worked great.

Anyone have any ideas?? This is driving me crazy!!