Here is a chance to get a Free Adobe Creative Suite 2 Premium Plus, it includes the Adobe Photoshop CS2 for the Windows and Mac. The other products included in this suit are the following
Adobe Creative Suite 2 (Windows & Mac)
Adobe Acrobat 3D 1.0 for Windows
Adobe Acrobat Standard 7.0 (Windows & Mac)
Adobe Acrobat Pro 8.0 (Windows & Mac)
Adobe Audition 3.0 (Windows)
Adobe GoLive CS2 (Windows & Mac)
Adobe Illustrator CS2 (Windows & Mac)
Adobe InCopy CS2 (Windows & Mac)
Adobe InDesign CS2 (Windows & Mac)
Photoshop Elements 4.0/5.0 (Windows & Mac)
Adobe Premiere Pro 2.0 (Windows)
System Requirements
Mac OS X v.10.2.8–v.10.3.8. PowerPC G4 or G5 processor
Microsoft Windows 2000/Windows XP. Intel Pentium III or 4 processor
To get this visit the following link
Get all these for free from here
You may have to login using an Adobe Id, which you can create for Free if you don't have one. You can see the download link and serial keys for each product which you can use to activate the products.
Read more about it here
This will be the best chance to get a Free Adobe Photoshop CS2 license key for Mac and Windows.