You MUST read (and follow the guidance from) these and their associated links:

http://www.sqlskills.com/blogs/kimberly/8-steps-to-better-transaction-log-throughput/

http://www.sqlskills.com/blogs/kimberly/transaction-log-vlfs-too-many-or-too-few/

I use them myself and advise every client I have to use them as well.