Every dvd burner has its strong and weak points. There are some that are very strong cd burners. Unfortunatlly I do very little cd burning so I cannot say which is the best for cd, but there are several very good burners you can get on newegg for about 40$ (liteon, nec, benq). If you like the plextor, get it, but if you want to go a little cheaper, there are plenty of dvd burners that are not much more expensive than a cd burner. Even though you only use cd now, I’m betting once you get a dvd burner, you will be suprized how usefull they are compared to cd (not just movies but burning data etc). Its worth a few extra dollars for the dvd burning capabilities.
Fyi there is no one best burner. there are defanatly some crap ones, but there are multiple good ones you can get cheap. Each has its strong and weak points and it is about imposible to say one is the best. Obviouslly cd burning capabilities is something you need to be a strong point. Look for a 2 sheep burner (has to do with with its ability to read cd copy protections).
A perfect place to look would be the cd freaks reviews. They usally do a very good job of identifying how good of cd burners the various dvd drives are that get reviewed. You could also use what people recomend to narrow it down, just remember, there is no one best drive so it is normal for diffrent people to say diffrent drives are the best. If you spend a little time to find out about the various features of drives, not only in reguard to cd burning, but also dvd burning, and then see which drive among the top few recomended drives fits your desired features and capabilities the most, you will be much happier than if you just make a quick decision.
My personal recomendations would be to look at benq, nec and liteon (plextors are good too but just my personal opinion, they are a tad overpriced). See what others opinions are an I think you will find that there are a few drives that are considered among the best.