There is no difference in meaning between upper and lower case, other than the fact that in a few cases the accents help in avoiding ambiguity.
In upper case there are no accents, therefore we do not make a distinction between monotonic and polytonic upper case. However, we do make a distinction between monotonic and polytonic capitals, when text is capitalized, i.e. only the initial letters are in upper case.
You can use this site for Systran translation http://babelfish.altavista.com/tr
but there is a link at the top of these pages for access to an English-Greek dictionary as well.
You can use Word to change characters from lower case to upper case (Format > Change Case > UPPERCASE), but it will not get rid of the accents; this has to be done manually.
Example:Polytonic lower case: ἀνθρώπου (=of a human) Monotonic lower case: ανθρώπου
Polytonic capitalized: Ἀνθρώπου Monotonic capitalized: Ανθρώπου
Upper case: ΑΝΘΡΩΠΟΥ