I dont know exactly how many photos will fit on a cd, but I know its at least a hundred or so, probably more. Do you have all of your photos in one folder? I would put a blank CD in and go to that folder, right click, hit "send to" and then choose the CD drive. See if that works.
If not, I would break up my photos into folders based on date/event etc. and then copy each folder to a CD and mark it. Thats what I do.
Another idea is to buy a USB jump drive. These come in all different storage sizes and you can copy pictures to them instead of a CD. My dad uses one of these to back up his entire harddrive, so I know they hold a lot. You can buy these pretty much anywhere (walmart. circuit city, etc).
You can PM me if you have questions..Im no expert. but after I lost my laptop last year with all my documents, Im getting good at backing things up!
-Haley