Sure.  I use winamp....www.winamp.com

Plug in the KRZR to the computer and open its memory with Windows
Explorer.  Drag the songs you want into the Winamp playlist so
they'll agree with what's on the phone.  Then click MANAGE
PLAYLIST and SAVE PLAYLIST, telling Winamp to save the playlist
to the phone memory so the phone can find it.  Motorola doesn't
seem to care where you save it, it finds it.

Of course, if you have a removable memory card, just take it out
of the phone and plug it into a microSD adapter and the adapter
into the computer.  I save all my music in genre directories off
the card's root directory so I can dump whole genres when I get
bored listening to them, without screwing around with the phone's
stupidly deep directory tree.  That way you can add hole new
directories you've already prepared on the hard drive to the
memory card without waiting for the slow memory card burning to
happen.  Move the whole directory to the memory card off the hard
drive while you go do something else.  Burning memory is
painfully slow.

DON'T forget to use the SAFELY REMOVE HARDWARE utility down in
the tray to DISMOUNT the memory card BEFORE just jerking it away
from the computer, which will trash the last files stupid Windoze
hasn't written to the card, yet.  SAFELY REMOVE HARDWARE forces
Windoze to write what it's holding to the card so the card can be
dismounted from the storage tree.

Do try not to attempt writing 4GB of music to a 2GB card.  LEAVE
some blank space on the card for the camera, too!  I leave a
couple of hundred megabytes so the camera has a place to store my
pictures of the massive accident...(c;

PS - WindozeXP is burning new songs to my ROKR Z6M 2GB card as I
type this...(c;  Playback is through the MotoROKR S9 Bluetooth
stereo headset, the finest headset I'm not embarrassed to wear in
public.  (They always look at you funny when you wear the massive
Sennheisers into a restaurant with that dreamy look on your
face...(c;)  I highly recommend the S9 if your phones are capable
of BT stereo.  The sound is LOUD and beautiful....  Radio Shack
had them on sale last week for $79 right in the stores!  You even
get an extra USB power supply that also works with the USB-
charged phones!

Larry