maddy i wont be able to suggest u which one to buy ... but definitely dont buy the samsung drives... its my experience that samsung has some design flaw which will result in the drive tray opening and closing , sometimes not reading the disc at all.
i am saying so coz i have one samsung cd writer in office, one dvd reader and one dvd writer at home and all three have the same prob.
mind u there is no virus infection... i took to service center but he too could not do anything.