My oldest app is from 1995 and is still being used today and growing. I can't recall precisely whether it was Access 1 or 2, I'm thinking it was 2. Can't recall the version numbers, then converted to Access 95/97 and then to Access 2003. At present our organisation is going through a refresh, upgrading from Windows XP to Windows 7 64 bit desktops but running Office 2010 32 bit versions.
Due to the refresh I now have to account for two versions of the front-end, one for the 2003 version and one for the 2010 version. For updates I utilise a batch file system. I had to rewrite the batch files to account for which environment the user is operating under which determines the correct file to be copied to the users account.
The number one advice that I would recommend is to document your code, it may appear self explanatory at the time but is a godsend when you have to make amendments; possibly years later.
On my development machine I run VMWare, Windows XP, Office 2003, and this is solely for this particular application. Hopefully, by the end of Feb, 2015, the refresh should be complete and I'll no longer have to worry about the 2003 version.