Refering back to the whole "life must be carbon based" thing it's not necessarily true. You can work things along pretty far substituting sulphur for carbon and ammonia for water. It just doesn't work so well in an oxygen atmosphere. In fact a while ago they thought they'd found sulphur based life forms here on earth, around volcanic vents on the ocean bed - so called black smokers. Silicon life forms are not impossible either..
try
http://www.daviddarling.info/encyclo...monialife.html
or
http://www.daviddarling.info/encyclo...liconlife.html
I'm not sure of the scientific validity of this site as I haven't read it all through. So consider this a disclaimer of any hoki bunkum that you may find.
I don't think that you will have to go all that far to find life - the best chance is right here in our own solar system on Europa, one of the moons of [jupiter?]. Whilst the surface is frozen over, there is strong evidence of liquid water under the surface, indicating that the moon has an internal source of heat. If there are black smokers there like there are on earth, then the warm, rich chemical soups they pump out may be ideal for the formation of life. It's considered that life first evolved on earth around these vents. Unlike as is frequently supposed, light is not necessary for life.