Okay. I would keep it simple and ask for further information if needed.
Dear So-and-so,
Wednesday at 1pm works well for me. I look forward to talking you about the X position. (or if you want to be more aggressive, say something like I look forward to showing you how I can increase the company's sales by doing XY&Z). Will this meeting take place at the office on Main Street?
Thank you,
Jackie
I wouldn't put too much into the e-mail. I know you should be selling yourself at every step of the interviewing process, but I think from her short no-frills e-mail, she just wants to know if you are available for right now.