They stopped producing Updates for Win2000 a couple of years ago.
I'd sudgest Windows Xp.
Its the most user friendly. And more compatible with Hardware and software.
And can be installed easily Over 98.
Regular updates keep the system running ok.
Then switch to Vista Later. When all the bugs have been ironed out..
You Can request when buying a New system That it Comes with Xp.
And i dont see why you cant just use the language bar to add Polish to the list of chosen languages.
Goto ( Start, Settings, Control panel. Select regional and language options.)
In Languages. Click Details. Add. And look for your Chosen Input Language
And look on the List for Polish. Add it, Select your Keyboard Language.
And Hey Presto....... :)
It puts an Icon on the start bar.
That way you can switch between English(Or any other) And Polish.