I like to get my spelling right. And at school I was always reasonably good at it. However, as I create documents almost exclusively on computers or mobile phones these days I've come to rely on spell checkers.
I have spell check plug ins installed for both IE and Firefox.
tinySpell is another useful looking app. It sits in your system tray and monitors your typing (a bit like a keylogger - erm... is that a good thing). Then, if you make an spelling mistake it beeps and offers you some alternatives. Not a full spell check but it could be a useful "as you type" reminder.
Spellbound is so much better, works with fox and thunderbird.
I tried it, but the only thing I have a problem with is that it spell checks my passwords. I'm not sure I want something to key log info like that.