There is no "response time" for CRT's. Response time is generally the time it takes for an LCD pixel to go from full off to full on (basically). CRT's refresh the entire screen *at least* 60 times per second, and up to/over 120 times per second, this is referred to as your "refresh rate".
A good CRT should last ~10yrs, but will slowly get a little more out of focus and flickery right from day one.
An LCD should stay sharp and clear indefinitely, but the backlights won't last forever. The longest we've kept LCDs in the office is five years (laptops) and we havn't had any LCD/backlight problems at all.
*Dual PIII-800 @900 i440BX and Tualeron 1.2 @1.7 i815*