Built a Win7 system last night, installed my D-Link DWA 552 Extreme Adapter and now everything just seems to be rubbish. World of Warcraft will post 2500+ ms, internet is dragging, and my life is crumbling before my eyes it seems.
Had no worries or issues with Vista or XP - in fact they ran fantastically. Thinking it's a Win7 issue having read over some other threads.
If it helps, i just upgraded a machine from Win XP 64 to Win 7 Ultimate 64 and the wireless card works exactly the same. In fact, Windows 7 had the drivers built in already and the wireless adapter worked upon first boot, none issues at all. Smooth sailing on WOW & LOTRO & COD & etc...
If it's a driver problem new hardware might solve the issue, but wastefully, as the original hardware is not actually broken. Try installing different or updated drivers for the D-Link from their website or firewall settings.