If your just getting into photography (like i am) i dont think you could really go wrong with chosing either a Canon or Nikon.
You will probably get the widest variety of lenses to choose from if you go with either of these brands.
Obviously they are upgrading models all the time so im not sure of whats what at the moment, especially with you being in Canada.
With Nikon, when i started looking about a year ago there was (on the entry level of the scale) D40 stepping up to the D60 then the D90.
They have varying specifications with more megapixles, settings etc.
Canon had the entry level 1000D stepping up to the 450D, and now the 500D, although i think in the US/Canada and other countries the 1000D is called a Rebel XS and the 450D is the Digital Rebel XSI.
I found a great site......
http://www.dpreview.com/ ....... they have reviews, information, sample pictures etc. from all the different cameras and lenses.
Here is a comparison of a few Nikons specs comparing them to your mums camera. The D80 seems closer to the D60 in specs.
http://www.dpreview.com/reviews/compare_post.asp?method=sidebyside&cameras=nikon_d40,nikon_d80,nikon_d60&show=all
Canon 450D and Nikon D60 Compared
http://www.dpreview.com/reviews/compare_post.asp?method=sidebyside&cameras=canon_eos450d,nikon_d60&show=all
As i said i was looking about a year ago, so models change and get faded out.
Best to check what you can get locally then compare prices and use
http://www.dpreview.com to compare the specs.
Then make your decision from that.
I ended up going with Canon, not for any faults i found with Nikon, ive just had Canons (just point and shoots, not DSLR's) in the past and liked them.