Some adapters not compatible?

I've got a client who has several old Dell Dimension computers (600 Mhz Celeron) in his office, with onboard Intel video adapter chipsets.

He bought a Sony 15" LCD monitor about 2 years ago, but it never really looked all that good on his computer. It suffered from some 'dynamic' interference problems, such as the image drifting a bit and 'fuzzing' when Windows dims the screen (at shut down). It is almost impossible to tune this monitor so that fonts look consistent across the screen. It ends up with vertical bands of darker pixels.

Now, he replaced the Sony with a new 19" ViewSonic and it has problems too. The new ViewSonic has a lot of ghosting problems.

The old monitor went to another Dell Dimension, and it has problems there too.

My question is, are some video adapters not suitable for use with LCD monitors? Do they have flaws that only show up when they are used with LCD monitors (not CRTs). Is it worth considering buying new video cards for these machines, or is the problem with the monitors?

Well, I discovered that adapters can have a big effect on how an LCD preforms.

The three older Dell Dimension (600 Mhz Celeron) machines that we were updating to new LCD monitors all had problems with fuzzy text etc. They all had Intel onboard video display chips.

I disabled one of the onboard chipsets on one machine and installed a new GForce PCI video card. This solved most of the bleed and ghosting and fuzzy text problems that we were seeing.

I've also been told that power supply can have a big effect on LCD monitors. Some of the cheaper machines that have power supplies with low power output can't put out the watts required by LCD monitors.

Am going to replace the video in the other two machines.