I think that before mankind sets forth for other worlds beyond our solar system (The Terra System for all Scifi fans out there) we need to learn how to take care of Earth first and live here responsibly before even thinking about going else where, also it is important that Mankind learns how to get along with his fellow man in a manner consistent with a space fairing race, thats what I think any way.
It doesn't necessarily follow that life requires water else where in the Universe, Earth is the only model that science has for life and so assumes that the Earth model is the same every where in the universe, how can this be?
According to classical planetary creation theory which one assumes these people are using the Earth model can only be true every where in the universe if these Earth like planets formed in exactly the same way the earth did, that is to say that its planetary disk form which it formed spun the same way, attracted more or less the same mass of material as Earth etc.
This model would also assume that these Earth like planets formed at roughly the same time as Earth did about 4.6 Billion years ago and have had similar geological processes as Earth.
As to the existence of life on these Extra-Solar Earths (ESE's) this can be done by looking for a Methane spike by analysing the light form the atmosphere of that planet using the method of Inferred Spectroscopy, Methane can be present without life but it is normally found as a biological byproduct.
Regards to you.
Cyber-Angel