Why do you want to put your pst file on CD? To archive, or move from one place to another? Your best solution depends on what you want to do. I often have to take things from one computer to another, and here is what I do:
1) be ruthless with your archiving - try playing with the autoarchive settings to limit the data stored in your pst file.
2) archive specific data - this is what you have done at present.
3) make sure that you have emptied the deleted items folder - I thought compactingdid this but it does not.
4) compact as suggested in the first answer - other routes to this tab are through tools - services - select the personal folder file you want to compact and click properties, or right clicking on the outlook icon on the desktop and do the same.
5) Make sure that you have unnecessary services emptied or turned off (eg journal or forgotten about tasks subfolders).
Another, rather labour intensive thing you could do is go through the email messages with attachmentsthat you have already saved somewhere else and delete the attachments from the message. this can be a pain, though, as it usually either involves saving the messages as text, or forwarding the messages to yourself without the attachment. It might guide you to messages that you would like to archive more accurately than date alone, however.
