Before we start discussing in earnest I'd like to sort out some technical problems. There seems to be some some kind of bug in my mail browser (MS Outlook Express 5) and in IE 5 as well. First, the IPA "Latin alpha" symbol (the RP vowel in last) of Lucida Sans Unicode isn't displayed; secondly, the colon-like length mark takes up way too much space.
I'm using MSIE 5.5 and the Outlook Express that comes with it and have no difficulty with the ɑ ("latin alpha") and the ɡ ("script g"), other than they seem a bit too small.  The length mark "ː" doesn't seem amiss either.  (Trying it on other computers that only had IE 5 showed the same results but some didn't show the ː length mark at all--they probably didn't have Lucida though.)
[mʲuk tʰeβɚ], I think