the mailto link?? IE7 and vista

In the past (XP) i was able to click a mailto link on any page and it would
bring up my Yahoo mail webpage (with the address prefilled...i might
add)...and off i would go writing and emailing! A pleased PC user was I !! (
i had downloaded a few programs - yahoo messenger- to get this to work- --
and it still works on my remaining XP machines)

Now in Vista (ultimate and IE7) it brings up the dread windows mail...not
what i want.... i want to click the mailto and get the yahoo mail page... can
that be done??? or has Vista eliminated that possibility??
thanks in advance!!
--
BCY1