Well, it depends:
sp_updatestats updates only the statistics that require updating based on the rowmodctr information in the sys.sysindexes catalog view, thus avoiding unnecessary updates of statistics on unchanged rows.
That is, if the rowmodctr is too low, the statistics is not updated.
Anyway, if you experience problem with statistics, you should try to add the traceflags in SQL Server 2008R2 (sp2) or later:
2371, Changes the threashold for auto update stats for large tables
2389, Changes the behaviour of known incrementing columns like IDENTITY
2390, Changes the behaviour of columns with incrementing values like a datetime column with incrementing values.
(Or wait 'til SQL server 2014)
atabase Developer 2008
MCTS: SQL Server 2008, Implementation and Maintenance
MCSE: Data Platform