Second: the thing is, you probably won't have that much use for it, because DVD-RW's compatibility is lower than normal, write-once media - I use it only for moving files from one computer to another

I once tried to write a DVD Video on this media to test it on my Playstation 2; it didn't recognize the disc, but on my stand-alone Pioneer DVD Player it worked flawlessly. So, the bottom line is, if you have the DVD-R/RW writer and already have one DVD-RW disc, you probably won't need more, but you should consider having at least one of them just to move files between computers (from yours to a friend's, if you only have one).

But the higher price and lower compatibility than the write only media, allied with the fact you can easily (and quickly) erase the data on the disc make it a bad choice for backups.