I was informed of 5 options.

Apache cTAKES™

MetaMap

LexEVS

http://lexsrv3.nlm.nih.gov/LexSysGroup/Projects/lvg/current/web/download.html

Apache OpenNLP

I also plan to parallelize an NLP library via map-reduce with hadoop.
However, I'm new to natural language processing, so I don't know which libraries would be simple to use.

I'm disoriented by a new platform. Can anyone help me orient my mind?