Try IE7Pro, a free plugin that adds spell-checking functionality, enhanced ad-blocking, and much to Internet Explorer.
Hope this helps,
or is there something else? (I was not allowed to enter all of it in thread title)
I had been using iespell for years, but found that at some point not too long ago it kept throwing an error message in my Windows Vista system.
Looking at the iespell site it would appear that the last update for them was a couple years ago.
Does anyone know if it now functions in Vista without errors, or if there is a comparable free utility available?