Wireless Network = super high CPU Usage?

[echolune]

I'm using a Sohoware Netblaster wireless LAN setup, and ever since I installed it my system has been running rather slow. Before the install, I was using some common ethernet card, and got an average of 2500 3DMarks (Celeron 850, 256mb ram, Radeon 32ddr). Now with the wireless card I'm getting about 1900. Also, the Windows Task Manager shows my CPU usage at nearly a constant 50%, with no obvious programs running. Just wondering, has anyone else experienced this?