The Mac should read Joliet (Windows95 and later) CDs without any additional extensions (though they are usually the 8.3 names instead of long filenames, I've found).
It may be that your daughter is writing multiple sessions on the CD, and not "closing" it. Doing this will cause other users trouble when they try to read the CD (this applies to Macs as well as PCs).
Roxio recommends always "closing" the disk if you need to read it in another computer.
I had a similar situation with a CD that I could not read from a Windows user. When I looked at the disk from within Toast, I found that there were multiple sessions on the disk. Only after the Windows user erased and re-wrote the CD from scratch, was I able to read it on my Mac.
In Roxio Toast (just for example), the options are to: "Write Session" or "Write Disk". Write Disk is what closes it. Write Session adds data to the disk, but leaves it "open" for more data later, but only from the same computer. The wording in WinXP is surely different, but if she is given any options, she needs to choose the one that does NOT allow data to be added later.
