Thanks for the info. I'm using my dvd-ram discs for data at the moment. I can use them as hard-drives just now using the HFS+ format but I only get 4.3GB on a 4.7GB disc. I heard if I used UDF, I would get 4.7GB.
However, I don't know how reliable the UDF format is. Some people say it's buggy etc. for using with data storage. Also, I don't know how to format discs as UDF on Mac OS X. I can do UFS but I didn't think that was the same thing because I only get 3.8GB with that.
I was also planning on burning the dvd-rams to dvd+/-r so they are more secure backups but I don't know whether to use the UDF format in toast or the mac/pc hybrid like I did with cds. The toast UDF format seems to work fine on the dvd-ram discs.