Is it possible to get accurate colors with ATI's catalyst control center? I can adjust gamma curves, saturation and hue.
No.
With Catalist you can roughly diminish saturation and so on. Unacceptable for photo quality. It's OK for games, where color accuracy is not important.
Videocard has no control over HD. But blu-ray players may have their own "catalists". It helps to some extent.
You can get accurate colors after calibrating HP 2475w. But that "accuracy" will be applicable to wide gamut content only (~5% of all available to display). To get accurate colors for the rest 95% you''ll need to go through further complications and limitations in the form of "color aware" applications (photoshop. browsers, etc.) with no 100% guarantee.
Why do we have to go through all that?
Because manufacturers want so.
Because an ultimate standard gamut H-IPS A-TW monitor costs about $1350, while the HP 2475w - about $900 - 33% less expensive (monitor+calibration kit+tax+shipping).
Many prefer to buy the monitor which is 33% less expensive, than the one which is 50% more expensive.
Even in the future, when wide gamut content becomes standard, the problem remains (less massive though). Not for those born today (playing teens with no history and no memory are safe!), but for those born yesterday.
My family photo archive is standard gamut and will remain so.
As long as it exists I'll need an ultimate standard gamut capable monitor.