I have a different experience with my HP ProBook laptop connected to my 24'.
I used VGA because the HP manual stated that max. resolution was only working with VGA port, while the HDMI port could only display 1920x1080. Sadly the images were not sharp enough (my laptop display is very clean), but the real problem was with text! It was so smooth that is become quite painful to read after some minutes! I had now the choice to return the screen to the shop, or buy a new computer, but luckily enough I did try a HDMI to DVI cable, and the result is really better! Luckily, the 1920x1200 resolution is supported by the laptop video card, contrary to what the manual says.
I never had this problem before with old displays, but as you know VGA is analogic, so the signal has to be translated 2 times, from digital to analog, and digital again...