New features in Photoshop CS4 and Photoshop CS4 Extended include a newly refined, tab-based interface in a single, integrated window, with self-adjusting panels arranged in docked groups. These features offer users greater efficiency, less clutter, and better results, faster than before.
There’s also the new Adjustments and Masks panels, and in Photoshop CS4 Extended, you have 3D editing and compositing power to paint directly on 3D models, create 3D animations, convert 2D images to 3D objects, and more; richer motion graphics editing; and more powerful and flexible image analysis and tracking.
Not sure if these are for you? You can try it out for free. Test drive it for 30 days and if Photoshop CS4 is too much for you, you can park it safely away and Adobe will not bother you. You only pay if you like it.
As a matter of fact, the 30-day free trial period is good for all of their CS4 products: Illustrator CS4, InDesign CS4, Dreamweaver CS4, Fireworks, etc. etc.
[Site: Adobe]