I continuously come back to ACR because of the colors, ease of layout, and overal look of the Oly images. I have installed RAW Shooter (too bland for me), SilkyPix, Paint Shop Pro, Bibble, Capture One LE (closest choice to ACR), and of course the likes of Paint Shop Pro 9, etc.
Yet each and every time (remember, Capture One LE comes very close), I wind up coming back to ACR. The colors are richer IMO and I've become quite accustomed to the layout, sliders, etc. I've used ACR with Photoshp 7.0, CS, and now CS2 - and it keeps getting better and better.
The key to purchasing photoshop is if you live near a college of university. If you know a student - and the book store has it in stock, you can usually pick up the Academic Version (same full version) for only $149.00 or so. Then you keep buying the upgrades (that's what I did - but then, I was taking some courses at the local university when I did this).
And the fact that Adobe keeps upgrading ACR is wonderful. You download it, unzip the file and then paste the RAW ACR plug-in in the plug-ins folder of Adobe...and wallaaaaaa, it's done...updated!
If you can't swing Photoshop, get the next best thing...Elements 3.0 which uses the exact same ACR plug-in (which is constantly updatable).
I'm telling you - again, as one whose tried them all and constantly experiments, Photoshop ACR just cannot be bested IMO. Sure, there are other views, but hey...I'm just weighing in here with my own opinion.
Have a great day...