Managing Transaction Logs - http://www.sqlservercentral.com/articles/Administration/64582/

Accidental DBA Guide - Chapter 8 - http://www.simple-talk.com/books/sql-books/troubleshooting-sql-server-a-guide-for-the-accidental-dba/

The only way to "truncate" your data file would be to delete data, shirnk the file then rebuild all your indexes which could created a bigger file that what you already had so I would leave that alone.

As for the log, I take it the recovery model of the database is in FULL, do you use logshipping or backup the transaction log regular for restoring purposes?