I know of two programs that can rip/play CD+Gdiscs. Can't say how good either might be.
- kTunes. A work in progress, but the feature list looks promising. Not free, but pretty inexpensive. If it works as advertised, it should be a great program. You can download a restricted trial version for evaluation.
- iStar. Don't know anything about this one other than the fact that the kTunes web site has a chart comparing the two programs
Note that you will need a CD-ROM drive that can read the graphical subcodes from a CD+G disc. Most of Apple's drives will not. Plextor drives usually will. If your drive can't read the subcodes, you won't get any graphics off of a CD+G disc.