During the re-install, I found that as soon as I installed the Drivers for my D-Link DWL-G510 version ‘B’ card the cpu usage spiked to 80%-90%. I uninstalled the drivers and the cpu usage dropped back down to 0%-2%. So the excessive cpu usage must be isolated to this card. I went to
DWL-G510 version B driver
and downloaded the latest drivers and the problem still persists.
For the record, my router is a D-Link DI-524. Is there anything else I can try? I’ve tried looking for a major firmware update but I couldn’t find anything.