Hey, well, using both my MAC and Windows XP SP3, when I plug my phone in, using .151 regular, it doesn't recognize either my memory card or the on-board memory, but I really need to transfer my backed up OBM.
options > memory
make sure media card support is on, MTP is on, Mass storage mode is on, and Auto enable mass storage when connected is set to yes.
Otherwise check that the USB driver is installed correctly in windows.
If all else fails try a bat pull to reset the phone, and reboot the PC.