The drive begins at the outer edge and since it has more sectors per cylinder at the same rotational speed it reads the data faster.
Optical drives often have to slow down to read from or write to the outer edges.
You can use a utility like partion magic to delete your OS partion, shift the 250 GB one, then create a new OS partion at the beginning of the drive.
Depending on how much room you have on the 250, you can shrink the 250 by 30 gb, and use Ghost to copy the OS partion to the beginning of the drive.
With some versions of ghost you may need to start an XP install then stop it when it starts to copy files, before you can Ghost over an existing XP installation. Otherwise all the files are there, but the OS won't boot?