Adobe Photoshop CS3

Photoshop is the photo editing tool for professionals. Period. Nothing else comes close. Photoshop CS3 is currently not the most recent  edition, as CS4 is the new version with a few new tweaks, but CS3 provides all that most pros will ever need. There are even a few things LEFT OUT of CS4 that CS3 provides(such as the one of the "extract" feature for removing backgrounds)!
CS3 is not the easiest program to grasp and you will need instruction from some source either through an online tutorial or a classroom setting.The intricacies of masking and layer editing are very involved and are not always a quick "click" to complete. Sometimes there are thirty+ layers involving hours of work for just one image.
That said, there are quick edit features for basic touch-ups and simple edit jobs.  Lots of "smart" features that automatically correct a multitude of issues. But, sometimes "automatic" does not do the job! You have to adjust images yourself using a wide variety of tools available. You decide which one would be the best in a particular situation. That's where experience comes in.
There is literally nothing you can not accomplish in image manipulation. The final results, dine properly, will look astounding.Everyone can imagine how to crop out an object with cut/paste type procedures...but CS3 has the ability to cut/paste images like people with wind blown hair onto other backgrounds where the hair shows the new background between hundreds of individual strands!
Basic cosmetic editing on facial features are a breeze. Pimples, wrinkles, scars...GONE...and no one can tell you did a thing to the picture. Now if they know the subject...well, there may be a question or two.
There are continuing ed classes offering something like a two weekend course covering CS3(or currently CS4). Avoid them. There is no chance whatsoever that two weekends can cover the information. No way at all. A basic course, covering "much" of the material would be a minimum of 25+ hours with lots of hands on practice. There are literally hundreds of menus and hundreds of procedures. Learn them step by step....bit by bit. A crash course would be worthless in the long run.
In the end, Photoshop CS3 will allow you to improve all your images, no matter how good they are to start with. You will also be able to rescue pretty much any image that contains even a small amount of visual information. Bring out images from shadows that were once almost pitch black! 
CS3 also comes with a complete photo management system (that works flawlessly with the main editing program)to hold all your files and arrange them in an endless array of presentations.File them by date, type, size, category, etc...
Photoshop has been improving the content of their editing material for literally decades. The original Photoshop program was placed on one small floppy disk...today's CS3 requires a DVD Hundreds and hundreds of to hold all the info in the current edition.
Buckle up and get ready for some intense photo editing!
It's a pricey...up to $1000+ on regular store shelves, however student versions can be bought for about $300(with a student ID) Adobe is very particular about checking those discounts at times! Also, the student version IS the full version and is not a scaled down edition. Everything is there.
So, sign up with your community college for a class and take advantage of the student rate(you'll need instruction anyway!...trust me)