could not restore 1st gen ipod touch unknown error occurred(2003)

See http://support.apple.com/kb/HT1808

Error 2000-2009 (2001, 2002, 2005, 2006, 2009, and so on)

If you experience this issue on a Mac, disconnect third-party devices, hubs, spare cables, displays, reset the SMC, and then try to restore. If you are using a Windows computer, remove all USB devices and spare cables other than your keyboard, mouse, and the device, restart the computer, and try to restore. If that does not resolve the issue, try the USB issue-resolution steps and articles listed for Error 1604 above. If the issue persists, it may be related to conflicting security software. If the errors persist on another computer and known-good USB cable, the device may need service.

Also, have you looked at the previous discussions listed on the right side of this page under the heading "More Like This"?