My company needs a digital SLR.  I have narrowed it down to several choices, but I have been out of photography for some time (not by my choice ).  I used to be a Canon man, but I would never turn down a Nikon.  

Choices are:

Nikon D1
Nikon D1X
Nikon D1H
Canon EOS1D
Canon EOS1Ds

All will be used and purchased from a reputable dealer. (KEH.com but I will take other suggestions)

Impossible to answer without telling us what u need it for.  otherwise, you're just going to get a lot of preference by ownership posts, which means nothing.

Quoted: Impossible to answer without telling us what u need it for.  otherwise, you're just going to get a lot of preference by ownership posts, which means nothing.

Well, the owners own several business' such as Construction, Real Estate and Private Investigations.

It would be a mix of all 3.

After we figure out which digital camera to get, I am getting a film SLR compatible with the lenses of the digital (EOS1D and EOS1 or D1X and F4)

Not sure why you narrowed the list down to defunct models.  Digital cameras are not something I would want to do that with.  Each generation has provided significant gains in image quality.  Especially with PI work, you will probably want to be able to shoot at high ISOs and even the new Rebels will blow away the cameras you listed with respect to noise at high ISOs.  With Construction and Real Estate, you'll probably want to be able to shoot super wide angle, that means a full frame sensor.  Of course you can always get the superwides made for smaller sensors (Canon's EF-S series, Nikon's DX) but then those won't work on your film camera.

I would get the Canon 5D.  It's about the same price as a used 1Ds but better in almost every way.  The ergonomics is also much better than Canon's 1 series bodies (which has always been a nit pick by many pros), I've put 30,000 exposures through my 1Ds MkII and still hate the controls.

For lenses, pick up a used Canon 17-35 f/4 and a 100-400.  

Quoted: Quoted: Impossible to answer without telling us what u need it for.  otherwise, you're just going to get a lot of preference by ownership posts, which means nothing. Well, the owners own several business' such as Construction, Real Estate and Private Investigations. It would be a mix of all 3. After we figure out which digital camera to get, I am getting a film SLR compatible with the lenses of the digital (EOS1D and EOS1 or D1X and F4)

Do you need image verification (pi work)? That might be a factor in what bodies you get as well.  

Where are the options for the Nikon D2 series? A much better camera than the D1 series. I would go for a D2Hs, used if the new price is too high. Smaller file size due to 4 MP sensor, which for me translates into faster workflow. Excellent low light performance, probably the best out of all dSLRs. I like the 11 point AF better than the Canon 45 point AF. The Canon system is actually slower due to the fact that it has so many more sensors to process. I believe the manual suggests to turn some of the points off to improve focus speed. I like the ergonomics of Nikon (alot) better, so pick up the cameras and see which one you like.

Both Nikon and Canon are good cameras and not one of them is clearly better than the other. It all boils down to a matter of personal preference, brand loyalty, and money.

Skip the D1 series.  If you can pony up bucks for D2x, you will be happy, otherwise teh D200.  With the D200 you get the magnification factor of 1.5x.  This will make the 400mm lens a true 600 mm lens.  Might be helpful in the PI stuff.  

Quoted: Skip the D1 series.  If you can pony up bucks for D2x, you will be happy, otherwise teh D200.  With the D200 you get the magnification factor of 1.5x.  This will make the 400mm lens a true 600 mm lens.  Might be helpful in the PI stuff.

No! The 1.5x crop factor does not "turn" any lens into another. It merely crops the image off so that it appears to be taken with a longer focal length lens, but the DOF, etc. lens traits will still be of whatever lens you are using.

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Digital Photography Review

There is also fredmiranda.com

What about the DCS 760?