Convert char to datetime. dmy instead of mdy?

I have an old application that runs on sql server 2000. I managed to get it working with sql server 2005 (for my new 64 bit windows 7 computer). I only have one problem: when I execute a report in the application (so this querry cannot be changed) which uses a date, the interpretation is wrong (mdy instead of dmy). The application cannot be changed, so how can I make sql server 2005 express use the dmy format? I'm a complete novice with sql server so please keep that in mind when answering.
In short I would like to configure SQL server 2005 express that it should interpret the date as dmy instead of mdy (as it does now). < ...