I have my DPI set to 144 and my display is very sharp and clear.  Just make sure you stay at 1920 * 1200 resolution.  This is known as the LCD's native resolution and you should generally keep it at this setting.  Generally the only exception would be video games.  The concept of a native resolution is specific to all LCD screens. 

An LCD screen is not like a CRT - you can't really change the true resolution since the pixels are manufactured at a set size.  When you change from the native resolution you are actually tellling the graphics card to do pixel interpolation.  This joins pixels together to try to simulate the desired resolution, with the result typically being less sharp than what you would see at the native resolution - especailly when it comes to text.

The only downfall with boosting the DPI is that windows does not fully support any DPI other than 96.  At higher DPI's you will occassionally notice web pages and appliations that don't render their screens properly.  Generally speaking the web pages / applications are still usable - but it can be annoying.