OS Differences for Development/Deployment

Alright everyone

I've got a .net program which is used on XP and Windows 7 and primarily it works fine. There are no massive issues between the two however there are some minor issues which I would like to be fixed if possible. These issues mainly relate to the programs ability to communicate with other applications. For instance, there are different versions of office used which affects exporting something to excel as some still currently use 2003 while others are on 2007/2010. This is similar with Microsoft Outlook with the different versions.

I know the explanation is brief and not detailed but my main question is should I be doing anything within the program or general setup to accomodate both OS. I've seen stuff relating to windows installer 4.5 but I'm not too sure if it's relevant.

Thanks