Is there a Multilingual Support for Tiger?

Yes OS X supports language and keyboard localizations. However, Macs will have keyboards that are specific to the country in which they are sold. If you buy a Mac in Ireland it will have a UK-specific keyboard.

I suggest you visit an Apple retailer and have this demonstrated for you so you can decide if it will work to your satisfaction.

I would also check your customs requirements for bringing the item back to Greece. You may still have to pay import duties and taxes that would make it less feasible to purchase in Ireland.

Check out this info on Greek Localizations for Mac OS X 10.4.

I really couldn't say, I don't know. I don't know if it's possible to get the keyboard changed, but if you could it probably wouldn't be covered under the warranty.

Basic localization just requires that you select the desired language when you install OS X. So all you should have to do is reinstall OS X and select Greek as the desired language. The International preferences can be used to make other changes such as number, date, and time formats and choice of keyboard localization.

From what I could tell, there is basic support in the OS, but very few applications are localized. Greek is in the list of languages you can select from the International preference pane, but I couldn't find many hits when I googled for Greek localized software. You don't have to reload the OS, just add Greek to the Language list in the International prefs. However, I think you have to use that patch on the site I linked to get the Finder into Greek.

Other software can be localized into any language if it was designed to be localized in the first place. It just takes some time to translate all of the strings.

Just to be clear about Tiger's official localizations, they are listed in the tech specs:

http://www.apple.com/macosx/techspecs/

In addition, the Tiger that comes with Intel Macs has Russian.

A Greek add-on is only available via Rainbow and 3rd party patches. Whether Leopard includes Greek localization I don't know. The new iLife 08 adds Polish and Russian (but not Greek) to the normal 15 localizations of Apple apps, and I suspect that may be the case with Leopard.

http://m10lmac.blogspot.com/2007/08/ilife-08-adds-new-localizations-iwork.html