Canon PIXMA Pro9000 "Windows Adobe RGB 1998 Installer Program"
The question remains , what does this download actually do
It installs the AdobeRGB ICC profile.
and why do we need it.
The chances of you not already having it are remote, if you have any photo editing software installed. But you can check: Control Panel > Color Management > then under the All Profiles tab, it is usually down near the bottom of the list.
If you don't know, then you probably don't need it.
I use photoshop CS6 at work with a Canon MarkII 9000 printer. I would very much like to know if Windows Adobe RGB 1998 is necessary.
Well, what working color space do you currently use in Photoshop? AdobeRGB, sRGB, ProPhotoRGB, AppleRGB, ColorMatchRGB?
Photoshop > Edit > Color Settings...
Canon offers Easy Photo Print which is a nice program and suitable for home use . They also offer Windows Adobe RGB 1998 software. Is this software necessary to produce accurate colors ?
It isn't 'Windows' and it isn't software, it is an International Color Consortium color space profile.