I like to use an editor to compose my Q&A's in an editor which can enable me to see a preview. I like to do this due to some non-technical reasons such as to avoid the hurry to click the submit button. I also would like to take a print out and read coolly before sending it to math.SE. So I request you to suggest me some editors of this sort.
which is a freeware TeX and LaTeX editor for Windows.
The trick will be finding an offline tool that supports both Markdown and TeX at the same time.
I would recommend a programmers' editor like TextMate or Vi or EMacs with Markdown and Tex plugins... but those are distinctly ASCII based and wouldn't offer a GUI preview.