There is nothing native to XP that will work like dd. Your best bet is probably to just plug the 300 in and copy whatever you can from the 80 to it then continue to use the 80 for the OS/programs and the 300 strictly for storage.
You won't find a good copy of ghost on limewire, but you may also want to look into downloading PE Builder which comes with a standard set of plug-ins...ghost is one of those. It takes a little reading to lear to use it, but it is the shizzle for rizzle. after you've configured the PE environment with PE builder, you just tell it to burn the disc, boot from the CD and you're pretty well set.