CDRW's have a life of something like 1000 rewrites. Unless you're deleting and updating files on a daily basis, it's probably going to last you quite a while. Additionally I believe that unless you actually format the disc, when you "delete" a file, it doesn't make the space actually available as you'd expect. It removes the entry from the table of contents, but newer files don't rewrite that space like they do on a hard drive. It uses the next unused space on the disc.