I thought id start this thread as I know there are a few fellow's with problems, and I know this has helped me a massive amount!
Im a Dyslexic. I have a built in spell checker on firefox.

Checks all my forums posts and its certainly improving my spelling steadily as I try to remember what I done to spell a word wrong. All it does is like Word put a red line under the word.
Obviously (id like to think it is) you'll need to be using firefox, and if you arnt... Eh? To download firefox go
here, it is simply better than Internet Explorer.
https://addons.mozilla.org/en-US/firefox/browse/type:3
Obviously look down to English (British)...
Hope that helps some.