Can you download DW CS4 and use the same serial number from a previously bought version? DVD no longer wants to work.

I have a new laptop and wish to install my Dreamweaver CS4 on the new laptop, and my actual CD no longer appears to be working.  The CD/DVD player in the laptop is fine and works with other media, so I'm sure it's the disc itself.  My version of DW CS4 has only been installed on one machine previously. Is it possible to download on line, and use the same serial number?