Ubuntu is nice but I prefer Windows personally as I have more experience in using it.
You can make any oprating system Islamic by adding language packs such as Arabic, Urdu, Farsi amongst others.
The Ultimate Editions of Windows Vista, 7 and 8 Pro offer language packs and you can add them easily to Microsoft Office easily for editing Islamic documents. I think it is very important to use technology for propogation of truth as Allah ta a'ala has ordered us to stay even or more advanced than the kuffar in technological advancements as Islam brought science to the world first via Quran Pak! Many secular scientists have made sajdah and became Muslims after they discovered scientific Ayat of Quran masha Allah!
[Shakir 08:71] And if they intend to act unfaithfully towards you, so indeed they acted unfaithfully towards Allah before, but He gave (you) mastery over them; and Allah is Knowing, Wise.