yeah, you need the ADB drivers. there's probably an easier way, but d/l Wugfresh's Rootkit. the drivers are included in that. http://goo.gl/tUC6BI didn't at first, but I just tried it with USB debugging on and same result.
Edit: I think my problem is my computer is not reading the device properly when its in bootloader state... Are there any drivers I need to download and install beforehand? It reads my phone when on, but not in the bootloader, any ideas?