Your question is off-topic in this Microsoft Word newsgroup, but see
http://support.microsoft.com/?kbid=932974 "You no longer have spell
checking capabilities in some languages in Outlook Express 6.0 after you
install the 2007 Microsoft Office system". You can reinstall the
proofing tools from an earlier version of Office if you have one, or you
can install a third-party spellchecking utility (there are many, some
free, some not, just ask Google).