Think twice about providing a CD for free. You should charge for that if you provide it at all.
That CD has value. That CD took work to make. But, moreover, that CD contains all your pictures in digital format.
If you want to sell prints, the CD is going to work against you. Your client can now print off 1,000 copies on her inkjet printer, virtually for free. Why should she come back to you to get prints that cost $10 or $20 apiece?
Providing a CD is a good service but, as I said, charge for it. (Like $50!)
When you do provide it, make sure the images are SMALL. Like 300 pixels horizontally.
You want pictures that she can look at on her screen or post on Facebook but you don't want her to be able to print out full size images that she could be coming back to you for.
ALSO, put your name, address and copyright statement in the metadata! If she's going to post your pictures on Facebook (et. al.) you'll want your name attached to them. 99% of the people out there don't even know what metadata is, let alone how to strip your name out of it.
You could put a visible watermark in the pictures or use a steganographic method like DigiMark or similar. That's up to you.
Bottom line: Watch out when you provide a CD!