Problem with CS2 or my camera?

Hi, guys. I have one problem and would like to ask you for advice. Yesterday was shootting portrait of my friend, with 400D, lens- 20mm f/2.8 (couse dont have much space in room to get fool body on the picture), had 2 D-Lites4 and they was on ful power. Have used flash meter, set up aperture, took picture - got perfect exposure and on the camera's screen lookt even to light, but when download to the computer - Oh My God! - pictures was too dark! Even on Photoshop showing that exposure is corect!?
There are few more things you would need to know: wasnt shootting in RAW couse of Vista in my computer, so why I've got so bad results? Or couse of camera (even on the screen pictures look even to bride), or couse of CS2 doesnt work properly with Vista?

When you look at the histogram in Photoshop, does the graph look weighted on one side?

If the histogram is showing that the image is indeed proper exposure/lighing...thi​s could be a monitor problem?

No, histogram looks just fine - graph look weighted... A monitor problem? What can I do abt it then?

This link should point you in the right direction...if it's the monitor.
https://photography-on-the.net/forum/showthre​ad.php?t=296149

Try opening the same image on a different computer and see if you're getting similar problems. Also, if other people use the same computer then your computer may have been sabatoged with little fingers adjusting the monitor.

No more sugestions?

Sounds like Monitor problem to me.

Why not post the picture here? Then if it looks OK to us, you'll know it's your monitor causing the problem.

Is your monitor calibrated? (By the sound of it not)
If not: Start there...

here is one example
wasn't shootting in RAW corse couldn't download to my computer (Vista) , and on camera's monitor looked bright enough, but not on my computer monitor! It looks like i do need to calibrate monitor...

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Looks OK to me. How much too dark does it look to you?

see, i dont know how it looks on your monitor, but on my looks abt 30% darker then on cameras screen! It looks diffently to dark, so i have to use on Photoshop auto levels at least to see properly picture to retuch.... I cant see the saim result I see on my cameras screen!

Another point: The camera screen is useless for judging exposure. Use the histogram.
I've got my camera LCD brightness turned all the way down. (I shoot in dark surroundings). Still the camera LCD displays more shadow detail then there actually is...