I can't update my Photoshop CS3 in order to open pictures made with Canon Eos 60 D
As Mylenium states, you need to be able to install and use the latest ACR, but it will not install in CS 3.
The Adobe DNG is about the only recourse, beyond upgrading PS to CS 6, and getting the new ACR.
I was faced with this twice in the last few versions - newer cameras were not supported in my version of ACR, and newer versions of ACR would not install, until I upgraded.
New cameras change their Camera RAW, so Adobe needs to update ACR. After a few versions, they write it for the then current version of PS, so users of legacy software are left out, until they upgrade.
You have the option to upgrade to Photoshop CS6 until the end of 2012 for the upgrade price. After that you'll need to pay full price. My recommendation: Download the trial for Photoshop CS6 and if it works well for you on your system, treat yourself to an early Christmas present.
The image quality improvements in Camera Raw 7, over what you've got, are alone worth the $199 upgrade price.
That was about where I was. I was "limping along" with an older PS, and older ARC, but then wife got two new cameras. Oh well, I just bit that bullet, and upgraded. [Unfortunately, I had to upgrade my Production Studio, though only needed/wanted PS, but such is life.]
All it takes is a good reason for an upgrade. It used to be my clients lined up, outside the office door, but upon retirement, I need to be prodded.
If you don't run afoul of the few egregious bugs (e.g., the sluggishness seen by Mac users, or a "can't get there from here" issue with a laptop display driver on a PC, then Photoshop CS6 is a really great package.
I've just processed a couple of astroimages tonight, and everything went perfectly. This is the most stable version of Photoshop I've ever used.
Being on a PC, and having a supported nVidia chip, I have not had an issue.
As for any sluggishness, I do keep an older version, or two, on one machine, or another, as my backup.
When I was active, I always had a previous version handy, for when the call came in, "This is a big rush, and we must make changes. We've already dispatched a courier, and he'll be there in 10 mins.!" Did I want to grab my new version of PS, the one with the GUI changes? No way - wanted a tried and true friend, to get the job out the door, and into the courier's hands.
With major PS changes, over the decades, I force myself to work with, and learn the new version (for better, or worse), until a deadline hits. Then, I am the ultimate recidivist - I go back to what I know intimately.
Now, I do not jump on every upgrade, like I did for many years. I have grown lazy, and do not have clients with open checkbooks. Still, when I need to upgrade (having wife with two new cameras, and my needing a new ACR will do it), I just upgrade.
So far, I have not really encountered anything, but MY not knowing where to look for something. I still have not used half the new features, but am working on that. I also spend most of the afternoon reading here, to learn where my "stuff" moved to, or what it's called now. Old dogs...
It's not terrible even if you jump a few versions; the Adobe folks don't want change a good thing, so much of what one expects is still where you expect to find it from version to version. A person who upgrades from Photoshop CS3 to CS6 will find the new Tabbed View, introduced first in CS4, and probably won't like it (at first), but it actually can grow on you.
With CS6 they've introduced this new "shape layer" abstraction of what was once a fill layer with a vector mask. Beyond that, I suppose there must be 3D changes, though I haven't the experience to tell since Photoshop CS6 is the first version I've moved up to Extended with. I admit, the 3D stuff is fun to play with.
Just to give you an idea of what I've been doing with Photoshop just this evening... My collaborator and I have been photographing carbon stars - red giant stars whose atmosphere contains more carbon than oxygen, and which are strikingly red. In this image the carbon star, SAO49477 is the red member of the close double just up-right of center. The red stuff between the stars is glowing hydrogen gas, singly ionized by starlight to emit a deep red color. Someday it will coalesce and make more stars.