Quite a few pros use the 20D even for sports, read the forums at
http://www.sportsshooter.com

Ron,
it won't be a camera or a set of good lenses which will make you a pro.
Professionalism is limited by the photographer, not his camera in most
cases.
There are some kinds of photography that require "special" equipment, but in
general I would say it's not your case.

Some nice ideas/motivation:
http://www.kenrockwell.com/tech/notcamera.htm
www.kenrockwell.com

Cheers,
Tony

   Stock: maybe, but Medium Format would be better
  Studio: but that depends on WHAT? you're doing in WHAT kind
          of studio for WHAT kind of customer.  Again, Med Fmt
          is prob a requirement and the 20D could be used in
          many situations as well
  Events: Yes, definitely (sports, social gatherings, concerts).  For
          classical music, singing, etc, a "quiet" camera such as
          a rangefinder would be preferable.  Weddings demand both Med Fmt
          and 35mm/digital depending on the package offered.
Fine Art: Medium or Large format.

You should perhaps "apprentice" for a bit to find your way.

MO.

Cheers,
Alan

Yes, a 20D should be fine. Even when you've gotten to the point where
you hit its limitations & need to consider going for one of the big
boys, it'll still be able to earn its keep for most purposes.

Pro's don't define themselves through the gear they use. If you sell
pictures for a living, you're pro. Whether those pictures were taken
with a digital, analogue, high end, entry level does not at all make a
difference.

BTW: I think digital SLR are not sufficient for stock photography.
Typical agencies expect 50 Megapixel and up, which you can currently
only achieve through digital backs for medium format cameras or high
end slide scanners.

Digital cameras are always going to push the boundaries until they become
the norm. Currently the boundary which separates traditional photography
from digital is a 4x5 inch film. Many studio pros use these "half plate"
cameras exclusively but generally they too are entertaining the ideal of
digital. I have 20D gear and for my 24" x 36" posters, I get exceptional
results.

Unfortunately the wall art photographs I make are still from traditional
film.Yesterday I ordered a 1Ds. I expect now to remove the last obstacle to
becoming 100% digital. The only suggestion I can make is to buy the most
advanced camera you can. Soon enough it will become obsolete and need
replacing. The real trick will be in choosing lenses which will move with
your upgrade bodies. Once again, go for what is currently best.

So here is some pertinent advise:
If you know absolutely how to market your work or, you have someone you can
pass the marketing to and they know what they are doing... Beg, borrow or
lease the best equipment you can find. The 3 things which make a successful
photographer in the order of importance are:

1. Marketing, 2. marketing, 3 marketing.

You'll note I said nothing about being able to take a good photograph. This
is because some of them most successful photographic businesses in the
world, are staffed by people with no unusual photographic ability. If you
can't sell your work, you'll just end up posting some photos shot with
horrendously expensive gear to "Shoot-In" for all the rif-raff to post their
(unqualified) remarks about!!! And one last thing... What marketing skills
do you have and what attention have you paid to this area?

Doug

Unless you are going to be using the camera where the camera is likely
to be damaged, I would invest your cash in the glass.   Really good fast
IS glass will do more to make better images than the 1ds.   Then when
you are generating income, you can upgrade your camera, and use the 20d
as backup...