I rarely see *any* CPU usage with single 6870 with a Pentium 4 CPU with Windows 7. In fact the system is used for basic graphics work in a production environment (Illustrator, Photoshop, etc.) and runs GUIMiner 24/7. The only time Windows Task Manager shows any CPU usage (1% for a half second) is when GUIMiner reports a share accepted.

I'm getting about 290 Mhash/s from this card, although that diminishes slightly when graphics work is being performed (even moving the cursor.) Al tasks seem to have priority over GUIMiner.

I'm just running the suggested "-v -w128" flags.