Hi Vida
Extended symbols depend on the font you're using as not all fonts have a
full foreign character set.
If your font supports extended characters, then you need to select the Basic
Greek character subset on the insert symbol dialog. Scroll down a bit and
you will see little omega - it sort of looks like a curly w.
If you can't find it that way, see if you have character map installed, go
to start > Run and type charmap in the dialog box and press return. You will
find it in the table of characters about a third of the way down. The unicode
character is U+03C9. Click on the character you want, then click the select
button, and then the copy button. This pastes the character to the clipboard
and you can then paste it into your Word document.
Genine