Making Data CDs

[Gerard Samuel]

Just getting into CD Burning with FreeBSD.
I have a directory of files with a total size of 540M (according to w2k).
I made an iso of the directory like ->
mkisofs -o files.iso ~/temp/files

Then I used burncd like ->
burncd -v -s max -f /dev/acd1 data ~/temp/files.iso fixate

Now, Im able to mount the CD in FreeBSD, and in w2k, and they seem 
similar, but the file sizes were way off.
According to w2k, the total file usage was 540M while the CD is only 40M.
Did I use the correct steps to burn this CD??

Thanks for any info you may provide..