How to write chemical formula in text box / Notepad ?

Answer 1

write the elements symbol with a gig font size and the subscript numbers with very small size or use word bad if you can not use word
or
use the paint

Answer 2

to get all sorts of symbols that you need to write a formula i think the character map will help you.
If you are running windows XP, go to Start > Run
and type charmap, just select the symbol that you want and paste it in notepad or wherever u want to.

If not, the charmap should be in accessories.
You can also download some free fonts from internet. just google for free fonts and sure you'll find them.

Hope this helps.