Welcome to the forum, basil!
Except for a few rare cases of the uber rich, there will always be systems out there that are better than what we own. It's just whether it's worth the resources (time and money) to acquire them.
My advice is this - if you're happy with your system, don't worry about upgrading. Just sit back and enjoy. However, if there are things about it that you think are lacking, then it might be time to start exploring a little bit.
I got a new receiver a couple of years ago because there were some things about my older receiver that I didn't like and hadn't liked for years. For me, it was just time, and I was extremely happy with the improvement in sound. As you mentioned, technology has improved, and I benefited from the auto-eq system in my new Pioneer.
By "exploring", I don't mean that you need to start doing hardcore auditioning, but just go out and listen to a few things (at stores or your friends' homes). I took a chance this summer and bought an external amp for my system. I had no idea if it would make any difference at all, but I was quite pleased with the results. Now, I did it because I thought my receiver was lacking when I turned up the volume - so I did have some motivation. I'm really glad that I got it, though.
One other thing. Try to not let all of the talk on this forum get you all geared up to go out and buy stuff. I have to fight that myself, and sometimes I fall victim to it. Again, if you're happy with what you've got, don't worry about what else is out there.
Adam