Eh, dun be crazy, never give softcopy, even if you do, have to make them sign proper agreements black/white. Must state what they can do with it and all others are prohibited and that the full copyrights lies with you (depends on amount paid).
If they want to hold full copyrights, don't let go until you're happy with the amount, give them the CRW if you want ;p
But after that you aren't allowed to use it anymore, so be warned (WTH cares when you've 30K in your wallet after selling that 1 image? :bsmilie: )