Mmmm.
Very good friend creates a bit of a problem. I have just been through some of the images on your web site. STUNNING. Now if I was a close friend I would be constantly comparing my results against these. Plenty of room for dissapointment.
Camera brand is really down to personal preference. How it fits in your hand, ease of operation etc. If the two of you regularly go out together, then going with Canon makes sense as you are familiar with it and can easily advise. The problem here as I see it is lens quality. The obvious quality of Nikon Foxy Bob's glass has had the same effect on me.
So I would say it is really a case of primary interest. If birds were the prime interest then putting as much of the budget into quality zoom glass makes sense and go with a Macro lens later. If its macro then the same rule applies.
Of course if you were going to move up to the 30D
...... that could help Karens budget but not yours.
Don