Dear Ken,
If you have backup Exchange database before delete the log, you can restore it from backup.
If you have no backup, you can only try to use Disaster Recovery Tools and Wizards to fix the issue.
For more information about Microsoft Exchange 2007 disaster recovery, please refer to the following articles:
Disaster Recovery Tools and Wizards
http://technet.microsoft.com/en-us/library/bb123476.aspx
Support WebCast: Microsoft Exchange 2007 disaster recovery
http://support.microsoft.com/kb/937563/en-us
If anything is unclear, feel free to let me know.
Regards,
Rock Wang
Rock Wang– MSFT