Regrettably so. The 'we know best' geeks at Micro$oft expect you either to us the utter pile of crap which is Windows Live Mail
, or to use Outlook.
I've always used Outlook Express and still do - it's fine for my needs. Unfortunately a bug in Office 2007 means that Outlook Express cannot use its English spellchecker, you need to acquire one from a third party source.
Wretched Micro$oft - why do they insist on fixing what ain't broken!