Ditto what GSquared said. Don't worry about the data in the table. Display is where that sort of things matter.

If you absolutely must tinker with the table, though, look into SQL Server collations. You might be able to apply a column collation that will change the look of the date data in the table. But that's an awful lot of trouble to go to. It complicates maintenance and will confuse later DBAs (especially if you don't document a rogue column collation). The best bet is to leave your tables and columns collated with the OS collation unless you have no other choice.