USB lag help?

I've been troubled by small bouts of mouse lag/unresponsiveness on the 2 USB mouses I've tested.  It was manageable, though.  Now, I've installed a PCI-E wireless adapter and things have gotten worse, including the rare bout of USB keyboard lag.

I have a Gigabyte AM3+ UD3 board, drivers up to date on both the board and peripherals.  Suggestions?  I'm guessing this is a bus problem and that I'll need a replacement board, but thought I'd ask around.

See if it helps moving the mouse/keyboard to another USB port, and make sure they're on the black USB 2.0 ports. If that changes nothing, moving the PCIe card to another slot is worth a try.

If the mouse has a setting (software or hardware) for the USB polling rate, try different values. 1000Hz specifically can be problematic.