new macbook pro + harmon kardon soundsticks = :(

hi-
i received a pair of harmon kardon soundsticks (old kind, not "II") 6 months ago and they worked great with my old g4 - started right away, never a problem. i just upgraded to a macbook pro (os 10.5.4), but when i plug in the speaker usb cord, i get no sound through the sticks (the power is on and running because i can see the blue light in the subwoofer) - what gives?
thanks for any tips,
hot_sake

Starting with the most basic of suggestions (apologies if this seem over-simplified but you did mention that on your G4 they started working "right away" via usb)

Go to "Sound" after launching System Preferences.
Check to see that HK sticks device appears as an output option with the Headphone Jack.
Highlight/Select the USB Harmon Kardon Soundsticks as your new output device.

...if you havent tried that already.