I was 18. My brother was a Marine stationed in Okinawa. I requested that he bring home a Nikon Photomic FTN. Instead, I got an Asahi Pentax Spotmatic. I never forgave him for that. 45 years later and I still have the Pentax.

I have the Sigma 70-200/Nikon D7000 combination and love it. Of course, I would have preferred the Nikon 70-200, who wouldn't? But at $1000 less money, I went for it, and frankly, do not believe that I gave up anything, except possible resale value, but since I never get rid of anything (all my closets are a testament to that) that wasn't an issue.
I did a quick side by side comparison between Nikon and Sigma, and in my unscientific testing, could not see a winner either way.

I have the D50, D80, D90, and D7000. Every one of them has been a jump over the previous one, but I have to say the D7000 was more of a leap. Go with the 7000. You won't be sorry.

"CAMERA!" is from Smugmug and free. Has nice options. Also "IPhoto" is very good and is $5.