On the box you type in, right next to the little 'smiley codes' link (upper right of the text body, below the subject box ) there are to little rectangles, the left one is block quote, the right one is 'paragraph quote' and the names should appear of you hover your pointer over it, click paragraph quote and it will slice the thing you're replying to into quote blocks so you can type between paragraph instead of just at the end or have to insert the < quote> and </ quote (remove the space after the bracket), can still be tricky. Be warned, it will eat anytihng you've already typed if you do this mid-message.

Hopefully I didn't just tell you what you already knew, if so, disregard. Took me forever to find out about the thing, but the 'paragraph quote box' is very handy

Edit: The block/paragraph quote boxes are only there on message you reply to that don't have *NM* in the title