Here are some
Alternative TN Monitors for you.
You can get two of them for about the same price as one from Alienware.
Again, I would recommend getting either the cheapest pair of TN panels you can locate or saving a bit more for a pair of IPS/PVA displays.
You are correct in you assumption, a smaller screen with a higher resolution will be very pixel dense and quite detailed from up close.
Even a 24" display with its 1920x1200 resolution, however, is quite detailed from close up...
Do not stress out about having a quick response time.
Your eye will not be able to tell the difference between a 2ms (.002 second), 5ms (.005 second) or even a 16ms (.016 second) response time.
FYI, the 60Hz refresh rate of nearly all LCD...