Check with valve themselves. According to there own survey, nvidia users outnumber ati users 2:1.
Yes, and how many of those cards are TNTs, GeForce MX's, or, frankly, anything but GeForce FX cards?
Most of them.
How many of the ATI cards are 9500, 9700, 9600, or 9800 cards?
Most of them.
What's my point? Simple -- nothing prior to the GeForce FX supported DX9 for nVidia. Nothing prior to the 9500/9700 supported DX9 for ATI. The non-DX9 path is a complete non-issue -- that's not what the game is targeted for, but it'll run just fine on it with fewer features. If you're going to upgrade though, then it was pretty clear last year who you should go with -- ATI had better speeds, better image quality, and decent drivers (which didn't need to cheat).
At this point in time it's a freaking tossup which card you should buy. The speeds are relatively the same as is the graphics quality. If HL2/D3 were to come out tomorrow then I'd go with an ATI card though, simply because they're available and they run cooler with less power usage.
I can see defending myself is pointless
Because you're being such a blatent fanboy it's disgusting. Hey, guess what -- my 3D video card history is V1->2xV2->GF2->GF4 Ti4200. And until the Radeon line came out I would never have touched ATI either. But they cleaned up their act -- it's now good hardware with decent drivers. Being a fanboy means that you've got your blinders on for no reason whatsoever -- is Nvidia paying you on the side? Will you die if you don't endorse them? Come on. It's just a freaking video card.
Fortunately HL2/D3 aren't coming out tomorrow. When they do finally lurch their way to store shelves then I'll evaluate the cards available then and buy -- and it'll be whoever has the best performance and quality for the price.