Photoshop CS4: Is there really a difference from CS3?

My mom and I bought CS2 when it was new and put it on our computers, and not too long after they released CS3. Months later my harddrive crashed and I lost everything. Luckily I was able to recover everything I lost, but when I tried to reinstall Photoshop it wouldn't let me because we'd already installed it on two computers. Luckily my boyfriend had CS3 on his computer, and was able to load it onto my computer. There were definitely a lot of features CS3 had that CS2 didn't that I use often. I haven't really looked into CS4 yet (but that vibrance feature looks pretty awesome! I'm sure I would use that A LOT), but if you're interested in learning about what the new features are, just go to YouTube and search "Photoshop CS4 new features". Then you can decide if it's worth it to upgrade, or if CS3 is enough for your needs. With every new version of Photoshop, they add a handful of new features and depending on your individual needs it's either very useful or is something you'd never use anyway.

Yes, you should definitely update from CS3 to CS4. CS4 has some new features like using your graphics processor unit (GPU) to take some of the load and speed up the process of applying filters, rotating, etc. CS4 is much faster and it seems that the Adobe has worked a lot on a new release. For example, I really like the content aware scaling feature which enables you to make every image wider without making objects wider, it is hard to explain, but imagine you have image of your friends standing and behind them you see the mountains, you can scale the mountains without having your friends scaled. You won't regret trying it. I'm not a Photoshop Pro but it is obvious that CS4 is better than CS3. You can download the trial to see if it fits your requirements.

Since no one has responded, I'll chime in with my 2 cent's worth. I don't use Photoshop but I do know software and, unless there has been a huge improvement in the product, there's no reason to upgrade. Check out Photoshop's website for the specifics of the update but, chances are, the improvements won't be something you can't live without.