I'll bet the new GTX 300 is going to be $499.99 when it first hits the shelves. I paid almost that much for my GTX 280 and at the time it was the most powerful GPU on the market.
I'm not going to get into the debate on which company is better etc etc. It always starts a War between the fanboys and I don't care for that. There are times when either company is on top and they go back and forth so often it's often hard to keep track. There is something to take into account though, the two most important things in my book when making a costly purchase such as this. Let me tell you a quick story.
(Note: This story excludes the rare occasions where you get shipped a bad part. It happens to both companies)
The very first computer I ever bought was a Pentium 1, 200 MHz. It had one of the first ever GeForce cards produced. Before that I had a VooDoo card in it back when Voodoo was number one. I got that PC when I was 18 years old and it didn't die until I was 29-30. It lasted through years of living in a trailer in the woods with no AC with Florida summers reaching 100 degrees. It ran in that hot room with no ventilation surrounded by smoke and ash around cat hair and dog hair and dust and dander. I think I even dropped it once or twice. It took a beating and kept on ticking.
During the years I used that system before I passed it down to my Mom it got plenty of abuse. I saw a lot of friends build new rigs and a lot of them went with AMD procs and early ATI cards because they were relatively just as powerful but notably a good deal cheaper. They argued "You're only paying for a name brand" with Pentium and NVidia. I argues "No, you're paying for quality and shelf life". Within the first 5 years I heard back from almost every friend I had who built a new rig saying "Damnit, my video card burnt out" or "Man, my proc melted my motherboard". Meanwhile my old beat up machine was still chugging. No parts broke or wound down. The last game I played on this system was Baldurs Gate 2 and the Throne of Bhall expansion. (which according to the system specs never should have ran on that machine)
To this day I always go with Pentium Processors and NVidia GPU's. I've only built one system with a AMD proc. I know from almost 15 years experience that these companies make parts that Last. Not being a rich S.o.b. I prefer quality as I can't afford to spend 500$ on a new GPU every six months. When I build a system I build it to not need a hardware update for at least 3 to 5 years and it's only possible to do that if you buy the top of the line.