Working without spellchecker isn't particularly difficult for me, but it does slow me down. Not so much the spelling part (my spelling ability is quite good) but rather, for catching all those little typos that creep in when typing at speed.

Insofar as proof reading goes, I read through several times with the notepad window re-sized in various ways. I find it especially useful to use narrow windows so that the text is seen more easily as individual words, and not large blocks of sentences.