i'd say go to control panel, brouwse around a bit, its somewhere, you can install any language, including aincient greek, chinese, hebrew and anything other than english (somewhere like 200 languages)

itas all there, but you migt need a windows cd (I even think it doesnrt even have to be a hebrew cd, just your own cd is okay..)
ofcourse, non windows/office programs will still be english or whatever language you installed them.