You need to add the Greek keyboard.
Windows XP
1. Choose Start > Control Panel
2. Select Regional and Languages Options
3. Click on the Languages tab
4. Click Apply (the files will install)
5. When asked to restart, click Yes.
6. When the computer restarts choose Start > Control Panel
7. Select Regional and Languages Options.
8. Click on Add other languages (this will open the Regional and Language Options Control Panel)
9. In the Text Services and Input section click Details
* Click on the Settings tab and then click Add
* In the Input Language menu choose the language you want to add
* In the Keyboard layout menu choose the keyboard you want to add
10. Click OK and then Apply
11. Click on the Language Bar button
12. Check Show language bar on desktop
13. Check Show textlabels on language bar
14. Check Show additional language bar icons in the task bar
15. Click OK
16. Click OK again
17. Restart the computer
When the computer restarts --
* You can change the language toolbar settings by right-clicking on the EN button in the system tray at the bottom right of your desktop.
* You can change languages by left-clicking on the EN and choosing a different language.
http://www.wellesley.edu/Computing/AlternateKeyboards/keyboard-setup.html