Okay, then what you are looking for is a DVD-ROM drive. A "combo drive" these days means a combined DVD-ROM and CD-RW drive. And yes, you can use your CD-RW to read CD's as well as burn them, but it won't read DVD's.
It has always been possible to read CD's in a CD-RW burner, but there was a time when this wasn't recommended, since burners were much slower and costlier than just plain CD-ROM drives. But those times are gone, and you can use your CD-RW as a reader without worries.
As for what to get for a DVD-ROM drive, here are some opinions from a thread in the DVD forum:
http://www.cdrlabs.com/phpBB/viewtopic.php?t=10254
cfitz