How Do You Tell If A Backup Is Currently Running, But Not Thru SEM?

Any ideas on how you might determine if a database backup is currently running? T-SQL script is preferable.

Background (SQL 2000 SP4):
I was previously running a script to backup the transaction log on a large database each hour. The script first looked in the backupset table in the msdb database to determine if a full backup was running by looking for a null value in the backup_finish_date column. Then the log backup would wait until the next hour to commence if it found a full backup had not finished yet. Some other cleanups and file numbering were also dependent on whether or not a null value was found in this column.


This process stopped working for me recently so I have looked closely at the inserts on the backupset table and found that the row for a given backup is not committed until the backup has completely finished. Therefore, the above process will not work as intended.

Thanks!