25ms is decent... it's been said that 16ms is optimal for gaming and DVD playback. But, the quality of the monitor makes a difference too. There are some that claim they see no ghosting/streaking on their LCD with a response time of 30ms. Mostly that's because different manufacturers measure response time in different ways.
There was an article here on AnandTech a few weeks ago that would tell you everything you want to know about LCD's. I can't find it though since it's been pushed off the first page and I can't find it by searching.