charging a razr v3 through USB 2

I work in the wireless industry, so the following comes from tests I've run on the RAZR and other phones:

It is not possible to charge a completely dead or low-battery RAZR through any USB port, PC or Mac. They draw too much current. There should have been an AC plug with a USB-style tip in your RAZR box. If not, you can buy one for about $20 at any phone store.

The RAZR's look very nice but they are complete trash when it comes to battery life, GSM wireless performance, synchronization and especially Bluetooth performance. My advice is to get another phone like a Nokia or Sony Ericsson. They aren't as snazzy as the RAZR but you'll get great all-around performance. Samsung's are up and coming, but still err too much on the side of cheap components like Motorola in my opinion.

Also, you can pick up a USB charger adapter for many phones (not RAZRs)at Brookstones.

Why can I charge my RAZR via usb through my PowerMac G5 but not my buddy's Dell Inspiron Laptop? Is this a recognized device, XP issue?

Thanks.

PowerMac G5, PowerMac G4, iMac G3 Mac OS X (10.4.7)

I suspect it has to do with a couple of things:

1) Some systems may allow more USB current draw than the spec mandates.

2) It's possible to charge a RAZR on some PCs if the RAZR battery charge is not too low (basically a trickle-charge state at high battery voltage vs. a fast-charge state at low battery voltage).