Anyone using an M-Audio Keystation 49e music keyboard with an aluminum PowerBook? I'm thinking of buying a music keyboard, and I like how that model runs from USB power. But I want to make sure my 15" AlBook can handle it--at least when the laptop's plugged into wall power. My AlBook can't seem to power my external USB HD, which my old Lombard G3 could power just fine, so I figure I'd better check. I don't want to buy that keyboard and then have to buy an AC adapter. TIA!