How are you booting Xboxhdm? Floppy, USB, CD?
Do you have only your new drive connected to the IDE cable?
Try building Xboxhdm with the minimum files needed.
I get the eeprom.bin file and the stock C files and build with that. The Xbox will rebuild the Udata and Tdata folders on its own. Then after the new drive is working, I FTP those files over. I then run my Krazie's Ndure exploit again and softmod the Xbox.