The thing about response times is there is no actual standard. So a 5ms response on one brand tv will be different than 5ms on another. Actually, it is alot like tire treadwear ratings.......no industry wide standard.
5ms, even black to white, is more than adequate for gaming. the 2ms response times, the 30,000:1 contrast ratios are all there for shout loudly at consumers. Better numbers MUST mean better hardware. Sadly, that isn't the case, they are just the easiest numbers for a layman to understand and quantify. Going on about the actual type of LCD screen isn't gonna mean jack to the regular guy purchasing, so they go for the numbers.
As for this whole situation, go with what Brownie says and just get a new GFX card. These days it is the gfx card (and to a certain extent hard drive speeds) that is the bottleneck in games, not the cpu's or memory. Either a newer GeForce or Radeon will do you well.