su -
apt-get update
apt-get install python2.5 python-tk python-numpy python-matplotlib prover9
wget -c http://nltk.googlecode.com/files/nltk-0.9.7.zip
unzip nltk-0.9.7.zip
mv nltk-0.9.7.zip /opt
cd /opt/nltk-0.9.7/
python setup.py install
python -m nltk.downloader -d /usr/share/nltk_data all
python
>>> import nltk.book