Welcome to CDF!
If it’s still working properly i’d keep it.
I have a Samsung 202 (the 20x variant of your drive) and while i think it writes CDs OK i’ve come to the conclusion that a pure ‘CD-only’ drive still can do a better overall job when it comes to writing and maybe also when reading. Plextor drives for example have always been relatively ‘unimpressed’ by audio-copy-protection schemes (i.e. no problems ripping audio to your HD). Also, as a general rule, it’s always a good idea to have more than one drive. If one fails to read an important disc, another may still be able to do so and safe important data.
As for writing look at this:
It’s four drives (3x DVD/CD, 1x CD) having written to different parts of the same CD. This is to compare how the drives writing capabilities compare on the same media. To explain what you see there: The first graph shows BLER-Error (green) and as you can see all drives show a similar very low error rate indicating a very good burn. However if you look at the second graph you’ll see there are differencies when it comes to Jitter (blue line, basically how ‘clear’ the signal quality is, as the data structure of the disc is read). The CD-only burner produced the best structures and thus it’s burn gives the lowest Jitter results compared to the DVD/CD writers.
Here is another example where a DVD/CD writer fares quite badly compared to another DVD/CD- and a CD-writer: http://club.cdfreaks.com/1749068-post91.html
The big question will probably be, if your computer still has an IDE-Port to connect the 40/12/40 to. Modern PCs sometimes come with SATA ports only. Adapters are available.