Photoshop (upgrade): earlier serial number

Greetings, I'm new to this great forum. I'm having a problem installing Photoshop CS2 on my new Macbook Pro. Because my version was originally an upgrade, I'm being asked for the original (version 6 in my case) serial number. I do remember not having a problem with this a few years ago when I intalled CS2 on my Powerbook, but my older version 6 and serial number is now long gone. One solution is obvious, but I'm not financially willing to purchase CS3 at this moment. Thanks in advance. - Roy

if you registered the product with adobe, they might be able to help you