As with anything you plug into your computer, you should take anti-static precautions.
We have just become so used to "plug-n-play" that a lot of us forget that (especially during cold dry months - aka Chicago winters) that static is abundant.
I always tell people to "
discharge" themselves before plugging anything into your USB port. (did that sound nasty? I didn't mean it that way - ha ha ha) - By continuously touching an un-painted metal surface of the chassis or the computer power supply case, or the leg of a metal table as you plug in the USB-passthru. (Granted, 99% of the world will not do this, but if you are worried about the motherboard... do it

)
Apparently Adrenalynn as sufficiently answered this question already as it pertains to USB2 - but if you don't know.... better safe than calling the GeekSquad!!
Hope that helps a little - Oh... and yes you can fry your motherboad by looking at it the wrong way too - so, yes you should take the necessary steps before practicing "safe hex"
Most importantly, can these PT's harm your motherboard? My PT was toast after one day's use and I'm waiting on a replacement. I am also waiting for an ac/usb adapter from, but if the PT gets here first I'll be tempted to use it with my PC. It would suck to burn up a $600 PC with a $16 PT ...