If the transaction log is growing a lot, two things. One, take more frequent log backups. That will free up the committed transactions more often. Two, maybe you just need a bigger log? Either you have lots of transactions or your transactions are big or your transactions are running long or all of the above. You just need a bigger log than you think.
"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