SATA/IDE Drive Letter Assignments

If I have 2 IDE drives, each of which has 2 partitions, so that they are assigned as drives:
C/E, D/F
and
I have 2 CD Drives, G & H

If I add an Serial ATA disk what letter is assigned to it? How are my existing drive assignments changed?

Yes I know I can change the drive letter in windows but I like to keep my window (WINXP) drive letter assignments the same as my DOS assignments.