"-4ms" is the DIFFERENCE between the response time of the two monitors; the Acer has 20ms response time and the LG 16ms (notice the minus sign before the 4 :P)
Im buying a LCD soon but Im not sure which one of this two is more suitable. I will use it mostly for gaming, watching dvds and surfing the net
Acer AL1731 http://global.acer.com/products/monitor/3_series.htm
LG L1715S
http://www.lg.ca/downloads/specs/computer/L1715S.pdf
These are the...