Lisa, sounds like a great plan and a fun event. Please be sure to let us know how it goes and your impressions of the meeting, etc.
As to scripting your intro speech...I found this really great pen-and-paper exercise that might help you, rather than copy/paste the whole article (which is quite long) I'll just post
a link for you.
I ran across
another article that puts it even more succintly with the question 'what's in it for me' - so rather than explaining that "you're a virtual assistant and this is what you do" you might want to come up with something that taps into and reflects the *needs* of your potential client.
AND - my own personal marketing 'guru' so to speak, has
a great article on elevator speeches that I'd highly recommend as well.