I went to Samsung's site and upgraded the firmware on my SD-612B to the lastest SD-612B firmware available. While flashing the firmware it said this drive does not support DMA. Setting it to PIO only in device manager as was mentioned in one of the other related threads solved the problem. Not sure if flashing the firmware was needed or not, but I'm just finally glad this drive works in XP.
If you're not sure what version of the SD-612 you have (B F or S), there is a sticker on the bottom of the drive that will tell you.