Andrew is correct. The backup you will want is the one from just before running period end on 1/31/2009. The backup from just before running year-end will do, but there might be some missing transactions that were posted to 2008 subsequent to running year-end.
If you aren't making backups prior to running period-end or year-end processing, now you know why you should have. If you did, good for you!
Steve