Honestly, the D200 and the 20d comparisons would not be fair to the 20d.
The D200 is a newer technology and is not what Canon has to rival the D200 as JP mentioned above. The real comparison is what Canon has in store for around PMA 2006. HOWEVER, both Canon and Nikon know this. Thats why surprisingly Nikon struck first and put the D200 out just after the 5d started to die down in hype.
Furtermore, both Canon and Nikon are putting the pressure on shooters to decide now rather then later. Nikon's double rebates end this year as well as Canon's single,double, triple rebates. They are trying to encourage people to purchase a 20d and the glass needed and cash in with the rebates now.
And of course, come spring 06' "Man, should I upgrade from my 20d to my "30d"" so to speak.
Originally when I went digital, I had a list of requirements I needed met. I was shooting with an F100 and had an arsenal of Nikon glass so I was invested to heavily on my equipment. And with options like D30 and a 10d available, nothing was blowing the Nikon mounts out of the water yet. So it became the D100 or S2 for my choices. God knows I was never going for the D1x for the pricetag.
I needed low ISO, PC sync on the body, and a Nikon F mount as my top 3 things I was looking for in a digital SLR. The D100 did not have an ISO lower then 200 on the D100, and required an AS-15 adapter to sync. So my choice to the S2 with 100 ISO, a similar feel being designed off an N80 body, great color and the PC sync and could take nikon mounted lens's as well as my SB-80 flash without having to invest in DX made it an easy choice.
NOW, with the D200 release, my eyes have wandered from me cashing in on the Canon 20d option. I could wait for the "30d" if i want, but *shrug* Nikon has the D200 out Dec 15th or so and rebates to boot. Then again, I could just buy the Canon lenses and not shoot them on anything [img]/ubbthreads/images/graemlins/smile.gif[/img]
The D200 with its lower ISO, PC on the body, and optional grip make it an appealing option for the Nikon prosumer shooter. I know canon is going to have another camera out to compete with the price range, and more then likely full framed CMOS versus the 23.6 x 15.8 mm CCD (DX format)sensor on the D200. By the way, this might take note, the size of the D2x sensor (23.7 x 15.7 mm) but it is a CMOS sensor. So, like JP said, I am wondering about noise levels on a CCD with that many megapixels. Cause, quite frankly, no CCD sensor on any major camera has taken such a high effective megapixel count. (Fuji S3 is labeled as 12 but lets face facts, thats two sensors 6mp each ....with no real noise
Im doing the wait and see. If you need something now now now and you love your Nikon glass I would say look into the D200, get your name on one of the lists that are out there cause quite frankly they are moving quite quickly. 20d is a fine camera now, I would say go for that if you really want Canon glass but be prepared to not kick yourself come spring and or upgrade.