ya solucioné el problema....
Solución: click derecho en la DB que quieren achicar el log, luego, all tasks y luego seleccionan Shrink DataBase...
alli, donde dice 10% le ponen como unos 50% (lean lo que les puse abajo y se informarán mejor) lean esto: Tips for Performance Tuning
SQL Server Database Setting If your set your SQL Server 7 or SQL 2000 databases and transaction logs to grow automatically, keep in mind that every time this feature kicks in, it takes up a little extra CPU and I/O time. Ideally, you want to minimize how often automatic growth occurs. One way to help do this is to size the database and transaction logs as accurately as possible to their "final" size. Sure, this is virtually impossible to get right-on-target. But the more accurate your estimates (and some times it takes a some time to come up with a good estimate), the less SQL Server will have to automatically grow its database and transaction logs, helping to boost performance of your application.
This recommendation in particular is important to follow for transaction logs. This is because the more times that SQL Server has to increase the size of a transaction log, the more transaction log virtual files that have to be created and maintained by SQL Server, which increases recovery time, should your transactions log need to be restored. A transaction virtual file is used by SQL Server to internally divide and manage the physical transaction log file. [7.0, 2000] Updated 8-4-2003
In SQL Server 7 and SQL 2000,
database and log files can be set to grow automatically. The default growth amount is 10%. This automatic growth number may or may not be ideal for your database. If you find that your database is growing automatically often (such as daily or several times a week), change the growth percentage to a larger number, such as 20% or 30%. Each time the database has to be increased, SQL Server will suffer a small performance hit. By increasing the amount the database grows each time, the less often it will have to grow.
If your database is very large, 10GB or larger, you may want to use a fixed growth amount instead of a percentage growth amount. This is because a percentage growth amount can be large on a large database. For example, a 10% growth rate on a 10GB database means that when the database grows, it will increase by 1GB. This may or may not be what you want. For example, a fixed growth rate, such as 100MB at a time, might be more appropriate. [7.0, 2000] Updated 8-4-2003
Mas Tips!!