Hi!
First of all, I HEARTILY AGREE with the endorsement of Bryan Peterson's books. All of them are fantastic! They are easy to understand, fun to read and make those somewhat intimidating, aw heck, let's get real here, extremely intimidating settings on the camera become more like channels on tv than like coded messages from mars.
Start with Understanding Exposure, then pick up Understanding Shutter Speed and you will be off and running. The up side is that you will suddenly find that you are much more able to make your camera do your bidding. The down side is that once you learn what your camera can do then you will start finding out about what it can't do and that is when it will start to get expensive

. Be prepared to start lusting after lenses, flash attachments, camera bags and even filters (yes, they are still very useful even with in camera enhancements and Photoshop) in a way that you never have before.
As for whether you should upgrade now or not, that is a tough one since it all depends upon your investment in your current system, your willingness to spend extra money and most importantly, your hoped for end result.
In some ways I would be the worst person to answer this question since I tend to jump head first into the deep end whenever I get interested in something new and it ALWAYS tends to wind up being expensive. I also am a confirmed gadgeaholic so I am easily seduced by the new and shiny.
That being said, if, after you have given the books a good going over and find that what is contained within actually interests you, you might give a look at not only the current models in the Canon family but also give strong consideration to the Olympus system. They offer 4/3 and micro 4/3 cameras (which has to do with the size and aspect ratio of the sensor which records the pictures). The camera bodies themselves (E system 4/3) vary in size depending upon the model and thus offer a variety of different feels for different sized hands.
The E-P1, E-P2 or PEN cameras (micro 4/3) offer the size of a larger point and shoot body with the interchangeability of a DSLR. They also offer HD video recording capability (if that is important to you).
One big plus for the Oly cameras, in addition to their in-body image stabilization feature (which means that whatever lens you attach to the front of your camera will be able to benefit from this feature whether it is an Oly lens, an older non digital SLR lens or another makers lens - all of which can be attached with the appropriate adapters), they also have a built in dust reduction system which automatically helps clean your sensor to help keep your pictures looking good. Oh, and Olympus makes some of the best "glass" in the business. These are the folks who make lenses for ultra super high end telescopes and electron microscopes and the like.
Oh, and one more word about the IS or image stabilization feature, since it is built into the body not the lens it means that you only pay for the technology once and not every time you wish to buy an additional lens which means that more of what you spend goes into the actual cost of the lens not the feature.
Olympus also has some really amazing color reproduction.
I know I sound like an Olympus Fanboy (which is a pretty neat trick what with my being a girl and all

and I am but it is because I have had an amazing time working with my Oly and therefore want to share my joy.
The truth is that whatever you choose, you can be happy with and if you do your homework before purchasing an entirely new system or choosing to upgrade what you have you will be.
And speaking of homework... I would STRONGLY advise you to head out to a good, reputable camera store (not just your local
Best Buy or the like) and get your hands on as many cameras as you can. Talk to several folks in the store including the customers, try not to get swayed by the sparkly displays and shiny banners and read a heap of reviews (dpreview is a great resource for this) on whatever camera you think you fancy. But make sure that you buy something that feels good in your hand.
I hope that helps! Take care, help lots of people and have a "Wonder"ful day!
Tisza