OK, I apologize for being mean. Your teacher probably knows more about photography than I do. Or at least I certainly hope she does.
Have you used a DSLR before? 75-200 is for making things that are far away fill a relatively large part of the frame. If the widest lens you have is 75mm, that will severely limit the kinds of shots you will be able to take.
http://en.wikipedia.org/wiki/Angle_of_view
The XTi does indeed have non-ideal ergonomics for large hands, but as a 6'1" person with a 6'5" wingspan who took about 1000 pictures with his XTi last Saturday, I can assure you that it's an entirely usable camera.
As for the "high tech" in the 30D that the XTi lacks, I can assure you that there is none. It's the same tech. Don't get me wrong. It's a better camera and I'd trade my XTi for one in a second, but if your budget is limited the differences are not worth it.
Filters are a poor solution for making a lens able to focus more closely (macro) or work at a wider or narrower angle. These are low-quality methods (albeit cheap) to achieve what is best accomplished with different lenses.
I have never used a DSLR before, due to the fact that everywhere I go that has some on display, they never have lens' attached...
I do understand what the lens' do, and what the 'mm' means
That is good to know, but I would like a camera that feels solid, I have read that the D40 does not feel very solid...
Just noticed the XTi does have that dust removing technology, Does the XTi take good quality shots? IDK why, but when I look at the XTi it doesn't look like a real DSLR, lol... and after reading around, lots of people recommend the XT over the XTi, do you have any idea why??
Thanks for the filters info...
Here is a list of the Nikon and Canon cameras that are in my budget (with there kit lens)
-Nikon D80
-Nikon D70
-Nikon D40x
-Nikon D40
-Canon 30D
-Canon XTi
-Canon XT
So basically, recommend one of those,