After you either backup your log or switch your database to simple recovery, you can shrink the log file. But you need to do one or the other. I have a blog post [/url]up the explains the problem and the best solutions.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning