Nothing earth-shattering to add but here is my view:
First off, I wouldn't run out and buy anything just because somebody said that somebody said that XY and z are the "standard tools that professionals use". That is not to say that there isn't a lot to be said for software that is widely used and, hence, comes with a lot of good information in books and on the web. This is one of the things where the Adobe products for instance are really great.
But the first thing should be to figure out what your use and expectations are. Or rather what your philosophy around photography is. A good friend of mine (and a very talented photographer with years of experience), for instance, has zero interest in any post processing (or lab work back in the days). His ideal is to come up with a shot straight from the camera that captures his vision. I on the other hand have no issue with manipulation after that fact. That ca be mild exposure and white balance corrections or taking a photo and turning into something completely different. The other thing to consider may be if you are looking to emulate any lab experience or if you're thinking straight digital. And lastly, do you have any established work flow, backup strategy and/or naming convention already?
I'd say there are generally two categories of programs: those that are mostly for viewing and organizing with limited (but sometimes really cool) editing options, often with really good batch operation control - and those that are strictly photo editing tools, traditionally used for painstakingly editing one picture at a time, using layers and having more or less unlimited options. And obviously the lines are getting more blurry lately. But the first category is great for organizing and batch editing or quickly editing larger numbers of pictures. It's like having a photo database with your own mini lab attached to it. The second category is like having a complete darkroom at home that comes with a free and personal technician.
The common Adobe programs for these two are Photoshop and Lightroom. Both have many advantages and disadvantages. And a lot depends on taste and how you answer the other questions above.
And then there are other suits and open source programs that kind of do similar things - though I don't think there is really a Lightroom alternative - but that being said: yes, a lot of people use and love LR - others just can't stand it. I like some aspects of it and find others revolting. I use it for quick edits of larger quantities. For everything else I stick to Photoshop, partially because I know it better, partially because the "non destructive" database approach of LR doesn't fit my established workflow. In any case, my recommendation would be to figure out your goals and expectations and then start with some of the cheap or free tools to see what kind of software works best for you. For example, if GIMP works for you then it may be worth investing in Photoshop one day. If you're happy with just a RAW converter the Canon software and a cheap or free organizing tool may just be it. And there are probably lots of others far and in between.
If the Adobe stuff becomes a serious consideration I recommend downloading their free full version trials and give them a good spin before putting down serious cash. And yes, the current LR3 offers for a hundred bucks or less are great bargains - and frankly that's about how much worth it really is if you ask me. But again, others just love it and it's all they need. Also watch out for Adobe's unfortunate policy in PC vs Mac versions. Switching is close to impossible if you ever considered working on both platforms.
