Backing up your photos

If its a CDRW like you say then jsut erase it in Disk Utility and then re burn all your photos (old and new) to the disk.

Just FYI, if you want to make a long term backup, avoid the CDRWs as they are more prone to developing problems than a standard CDR.

i usually just drag the entire iPhoto Library folder to back up. coupled with iPhoto Library Manager, i can maintain/backup multiple libraries and/or launch iPhoto using any of the libraries.

You might want to consider exporting your photos to a seperate folder to backup instead of just doing it through iPhoto, thereby avoiding iPhoto's complicated storage structure. Plus side is that you can easily browse through your backup photos on machines without iPhoto installed but you then lose the ability to have your CD treated as an iPhoto library.

I actually use iPhoto Buddy to maintain multiple smaller libraries and burn photos to disk as both an iPhoto library and exported photos. Obviously depends on your individual album size but works peachy for me. 🙂