Can't calibrate a monitor on win7

I have never been satisfied with the color on my Win7 professional 64bit upgrade on a vista machine.
I am a photographer and use photoshop extensively. Here's what I've tried:
the Lacie professional lcd monitor with its own calibration couldn't produce the brightness necessary, so I switched it back to the XP and ran a calibration. It was dead on.

I have tried calibrating the Lacie Blue Eye with the original driver and then with the new driver.

I just bought a spyder pro4 and calibrated the Samsung on the Win 7 machine, it gave me caution warnings that the brightness was too low and could not come close to the gamma I need. Also had a magenta cast.

Both monitors will calibrate with different hardware calibrators on the XP and will not on Win 7.
So it has to be a problem with the Win 7 machine. The video card I have is AMD Radeon HD 6570.I tried upgrading the driver, but the site is strange, it wants to upgrade all my drivers and charge me. I would rather buy another card than play that game. If it's not the video card, I am clueless. The newer Painter and Photoshop will not run well on the XP machine, so I have to either solve with current Win7 or upgrade to Win8 or buy something else.

Any thoughts on this will be appreciated.

Thanks, Carol R

Reporting back:
It was the video card, I did finally get to the manufacturer's site, got the most recent driver and installed it. Thanks to the members who helped me with this.