Here is a start...
This is for those upgrading from P&S digital camera to a Digital Single Lens Reflex (DSLR) camera and please do not let this deter you from getting a DSLR, but these are the facts...
1) A DSLR is named such because it is in a really easy way to describe like a periscope and the bottom mirror moves up to expose either the film (in 35mm sense) or CCD/CMOS chip as we have gone digital now.
2) First you will probably realise that the pictures are not as sharp, crisp, etc as the ones you are used to from the P&S camera. The P&S cameras have a lot of incamera sharpening and stuff applied already so you can shoot the picture, and use it straight away to print or e-mail with as little fuss as possible. It will not always be that easy with a DSLR. These picture can take a lot of time in the beginning to get it right, but with a good workflow (what you call the image manipulation) it can be done in minutes. The reason behind this is to let the photographer manipulate it to their liking. You will need to take this seriously. To get set up will cost easily $2000 or more area to get set up from scratch for the body alone and why be nonchalant? Have fun! It is really fun to do this once you get the hang of it! There is no subsititute of practice. The best part of digital is that there isn't any film to be developed, or price to pay for developing and you do it all. Believe me I have gooten plenty of bad pictures, even digital and that is the best feature to be able to delete it and try again and again till you get it right and costs you nothing. The cost to print the average picture isn't really that much, in your local currency! Here in England, an 8x10 will cost about £2 from Tesco (a grocery store with film developing capability) or insanely cheap like 50 pence (in England) at the most for a 5x7. In the US there are many places you can go and I have heard you can go to Costco, Wal-mart, Sam's Club (in the US), and many more places to get it done and again for relatively cheap, possibly a few for a dollar, if not 1.
3) This is far from the end of the spending provided you are starting from scratch...
You will need at a minimum a Compact Flash (CF) card (2x 512MB CF cards (reccommended) work really good and at least 2, just in case one fails and you have the back up), extra batteries, and of course lenses. Lenses can get really expensive with Canon L glass (lenses). The camera will not work without a lens! There are optional extras like spare batteries, the vertical grip, BG-ED3 for 10D or BG-E1 for 300D, flash, cable release and much more.
4) Getting back to the mediocre lenses, you can't afford to skimp on them. Your pictures will instantly speak the lens you use in front of it, mediocre or great. They are the next most important thing to to the camera itself and will not work real well with a mediocre lens. This is kinda like buying a sports car with a real weak engine. In both cases you will not get the full enjoyment out of them. There are some great F4L lenses out there if you aren't willing to shell out over $1000 a lens. These ones are about 1/2 the cost as their F2.8 counterparts. There are also 3rd party lenses available from Sigma, Tokina, and others. These are more budget oriented.
There is just so much to tell, hell, you can literally write a decent sized book on it!