This is a good response. I still get frustrated with flash, and had not yet
heard of viewtube, I'll try that out.
Two things I'll add:
I'm very low-tech and have still managed to convert from a windows 7 pc
without too much trouble. Honestly, the most difficult thing about my switch
was getting used to flash player not working for a lot of videos and whatnot.
Since it seems like a big step at first, what I did was install it alongside
windows 7 so I could have something to fall back on if I needed it. I know
some people are very hardline about this, but it can be difficult to make the
transition all at once. I'd keep OSX there in case you have the need to go
back for flash player or skype, and over time you'll get used to those things
being gone.
Also, the main thing you'll want to watch out for when trying it out is that
some network card drivers are nonfree, so it may be impossible to use wifi
without buying a peripheral. I converted my windows 7 pc without problems,
but if you can't use your wireless, you may need an adapter from the
thinkpenguin link on the right, they're about $50 I think. If you have this
problem and that's not in your budget, you may be forced into using an
operating system that is not fully-free. Different people have different
opinions about this, but I think this is a realistic problem, and in this
case your best option would be to try a different distribution, like Fedora,
which does make some attempt to promote free software while keeping non-free
parts that are required by some hardware to run.
As onpon4 said though, you can test to make sure everything works before you
install, so just booting from the CD puts you in no danger!
Good luck!