Aye the whole scenario about having a CD and a CD player on a desert island doesn't really work because:
a) if you got marooned on an island, how did you manage to keep the CD player dry?
b) however you managed to keep the CD player dry, surely other items were in there and hence they would also be saved (potentially other CD's?)
c) realistically how long will the batteries last?
d) you never said anything about having earphones/speakers to actually play the music
e) the music would help you maintain your sanity, but once the batteries run out you would most likely kill yourself
Putting all that aside and throwing all logic out the window however, i would probably have to go with SlipKnoT's
Iowa. The lyrics and style of this album would most certainly go with the frustration and anger of being on a desert island ^_^
Although, this is only under the assumption that:
a) you actually mean 1 single CD and not an album (some have 2 CD's)
b) you were referring to commercially produced CD's only and not ones burnt yourself, which i would much rather have preferred (being able to hold 700mb of music instead of 70 minutes)
c) i didn't have my iPod with me