Check your keyboard settings - it looks likely that your keyboard is set to US and not English keys
Once set to English settings the euro symbol can is usually Ctrl-Alt-4
Re letting other users access a program on your laptop - you could install it on eveyone's pc or install it on a server - however, you need to be sure the licence on the program allows you to share it with other users
Re Keyboard Problems.
If running Windows XP,
Go to Control Panel
Open Regional and Language Options
Select Languages tab and click details
Set your preferences e.g.
Default input language = English (Ireland) - Irish
Installed Services = EN English (Ireland) Keyboard Irish
Other Windows versions should have similar settings.