Yes good point TaoTeJared and Nikon always has better resale value as well. So for $300-400 more you can pick up the Nikkor 70-200mm VR 1. That being said I know the new Sigma 70-200 OS is fantastic, and so is the "Bigma" for that matter. My favourite Sigma has to be the 150mm macro though.

If you are on a budget, you can find a Nikkor 70-200 VRI for about the same as the Sigma. Nikkors always work better with AF and VR in my experience at the pro level glass.

I have had spotty luck with Sigma products, mostly bad but have seen some good as well. Resale value drops fast on Sigma lenses, you may want to look for a used one on ebay. Might save you a couple of hundred and if you don't like it, you won't be out so much money.

It's not smart to get into the "pixel peeping" this is sharper than that debate. Realistically, they are all sharp, and you will not be able to tell a difference. For basketball, AF means more than sharpness.

You have been asking about high isos in your other thread and commenting on freezing action. Have you looked at getting maybe a 85mm 1.8? I have the VRI 70-200, and love it, but for bad lighting with movement I throw that and my 50mm 1.4 on quite a bit. If you are on a budget and want to upgrade your camera this year, that might be a cheaper option for now and save up for the 70-200 down the road. You could always rent lenses for a couple of days to see if you like it as well. You can rent a Nikon 70-200 vr1 and a 85g 1.8 for about $80 for 3 days over at barrow lenses. Might help you figure out what you want. Small price to pay to try a couple of lenses that you will have in your bag for years.

Just to avoid confusion, Sigma has had several iterations of this lens. As DPReview summarized them:
70-200mm F2.8 EX APO - Original version, minimum focus distance 1.8m (1999)
70-200mm F2.8 EX DG - Addition of 'digitally optimized' lens coatings to reduce flare (2005)
70-200mm F2.8 EX DG Macro (HSM) - Minimum focus distance reduced to 1m (2006)
70-200mm F2.8 EX DG Macro HSM II - Improved optical performance (2007)
70-200mm F2.8 EX DG OS HSM - All-new design with built-in Optical Stabilization (2010)

I own the stabilized, OS HSM version personally; my office has the 2006, non-OS, HSM version. I love using both of them. The non-OS version is lighter and shorter, making it a bit more fun to actually use (My coworker keeps the older Sigma 70-200 on the office camera all the time now, but before we got it, he very rarely used the old, unwieldy Nikkor 80-200 f/2.8 it replaced). The OS version obviously has stabilization, which is a great advantage for hand holding in low light, and is probably worth the extra weight, length and money in many situations. For shooting sports though, I usually keep my shutter speed above 500, and the faster shutter speeds tend to equalize performance between stabilized and non-stabilized lenses.

I'd recommend either version without hesitation. One of the student photographers I work with owns the Nikkor 70-200 VRII, and I haven't seen any difference in the image quality--if anything, his basketball shots are usually softer than mine, but that's down to technique, not technology. The only things you miss out on by not buying the Nikon are:
1. Weather sealing (not a huge issue for indoor shooting).
2. Focus limiting (I do wish I had that, but I prefer having $1000).

Don't even go for the OS. I have the first generation 70-200 Sigma. It is an incredible lens. I can get sharp shots at 1/50 of a second. Don't hesitate to buy either Sigma telephoto, either the first generation or the second generation OS.

How about looking at this thread and see if it helps. Maybe there is some new info out there as well...

http://nikonrumors.com/forum/topic.php?id=2804

And, sometimes a forum search is nice as it will get you what you want quicker.

Hey guys,

Long story short, sold my D7k and picked up a D5100 while I await the D400 (or whatever) next. I currently only own a Sigma 17-70 and Nikon 35/1.8.

I love my Sigma, it has been a GREAT lens.

I am in the market for a 70-200 2.8 Tele and I cannot afford the Nikon VRII version. So, I'm thinking about geting the Sigma OS model and wanted to know what you guys think of it.

I know that it's a little less sharp at 2.8 than the Nikon, but how much? is it something USM can overcome? Would the Nikon VRI be better than the Sigma OS?

My main use for this lens will be High School basketball. I will also use it for outdoor events like parties and portraits.

Currently the Sigma is on sale for $1300 USD.