With the current trend of Small Form Factor PC's nowhere near its end, space, or lack there of in a PC can be a real problem. Combo drives help alleviate this problem by combining DVD and CDR/RW functionality into one. They are note quite as convenient for doing CD-to-CD copies, but combo drives like the X48 only occupy one 5 1/4" drive bay.
Any SFF PC user will tell you that real estate inside the PC can sometimes also be a problem, which is why we're happy to see the MSI X48 is nice an compact, length wise. To top things off, you can also change the front bezel of the drive from white to black.
The MSI X48 is not the fastest CD-RW on the market, with only a 48x CD-R, 24x CD-RW burn speeds but I doubt you'd notice the difference between 48x and 52x anyway. The X48 supports all the popular writing methods including Mt. Rainier.