Well I went from a Fuji 7000 (with around 30k shots on it) to a Canon 30D. It came with a 17-85mm IS USM lense (which I have found excellent, except for a bit of CA under harsh contrasty light).
I then purchased a battery grip with extra genuine battery (over 1000 shots). Excellent for portraiture mode - which I use a lot in my passion. And a 580EX for fill flash when shooting PJ.
Other lenses (before a trip to NZ last year) were a 10-22mm WA (brilliant for buildings and wiiiiddde landscapes) and a 70-300mm IS as a general walkaround lense. Also purchased was a 50mm f/1.8 prime which is just so much fun!!! All three zooms cover 10-300mm and I think for the money are just wonderful for walkaround shooting.
Since then the L bug has hit. My first purchase was a 70-200mmL f/2.8 IS specifically for portraiture and low light use (as I have done a few portrait shoots with it as well as award nights at my daughter's school where I seem to have become the defacto school photographer...). It is exquisitely sharp even wide open, and the IS is just awesome.
Next purchase was a 50mm f/1.4 as it is sharper than the 1.8 wide open, as well as the USM is wickedly quick! Goes to show - the primes are fun!!!
Last purchase was a 24-70mmL f/2.8 again specifically for portraiture. I have found that this lense is not as easy to use as the others (less keepers), but that is just my lousy style that I have to better - not the lense. But the contrast, colours and sharpness across the image are what makes it really stand out compared to the 17-85mm. But since it weighs a bit more, I still use the 17-85mm as a general walkaround lense.
My next purchase will hopefully be a shoulder bag for the L and prime lenses (portrait shoots generally don't require a backpack like I have for my walkaround lenses), as well as an 85mm f/1.8 prime again for the fun of primes!!! Once you get the prime bug, it's hard to shake...
Not much of a review, but more of an insite into how a hobby can become a passion!