simple... this works with any droid!

1) make sure SD card is in the phone
2) go to settings... applications... developement... and check ON USB debugging... very important! LEave it ON!
3) connect phone to PC via usb cord...
4) swing down notification bar... click usb icon
5) choose Mass Storage Mode...
6) phone may powercycle (typical for first time connection)... also, phone will auto install drivers onto pc/laptop/mac... this takes about 3-5 mintues... no worries...
7) after all that is done, open your windows media player... it should read the thunderbolt.... go to sync tab.... and sync.... WMP will also sync your videos and pics too if you choosed to do that... if not, only mp3s will sync to SD card Music folder... sync usally takes about 20-40 minutes, depending on your library...
8) now, if pics and vids didnt sync with WMP... then do it manually... open the vid and pic files on your pc ... now go to MY Computer... like a USB jump drive, your phone is now an "extra" drive listed... click it... copy/paste you pics to the "picture" folder on the phone... copy/paste videos to Video folder on the phone... after all that... disconnect phone... POWERCYCLE (always nice to do that after any transfer to make sure data is stored correctly and not defragmented by user data after the disconnect (i know im paranoid, deal with it lol lol lol )

and walls... your done... make sure you mp3 stock player rescans ALL folders (you'll find this in the mp3 player app settings menu "rescan folders"... enjoy the Thunderbolt!