What could be the repercusions of using PocketPC 2003 apps in PocketPC 2002?

I recently bought an iPAQ 3850 which has the 2002 OS, but I’d discovered lately that HP removed the update from 2002 to 2003. So all the apps for 2003 that I’ve downloaded recently might not work or will, anyone have any suggestion what I shall do?

Please don’t tell me to buy a new PocketPC since I don’t have money now.