No emails at work (or even not at work. Email kills attraction). If you HAVE to reply (here you should) wait awhile and simply say something like "thanks!". Also if she calls you, keep convos extremely short and professional.
Let her physically pursue you. If she tries to get you on her facebook or myspace or anything, don't. Stay away from that stuff. You and I as men can talk over the internet and it makes for good discussion. It doesn't make for attraction with a woman however.
At work, it's ALL on her. There's a double standard for men and women. If any moves are to made, they will be made by her. And if she is interested, she WILL arrange to be with you. She will probably start by finding completely lame excuses to "get your help" with something, or to ask you questions that she easily could figure out on her own.
Then it's most likely she'll pursue you in a "safe circumstance", meaning she'll probably arrange lunch with you and some co-workers, so there is little pressure on her (and you) and it doesn't feel like a "date".
Over time, if she treats you with good behavior, consistently (good luck with this one) and does not literally freak out that you won't pursue her, is when you have a better idea of what she is like as a person, and can make a better choice if she's worth risking your career or work reputation over.
That's ONE WAY to do this. The OTHER way, is the "I don't give a ****", chase her around, try to (or do) hook up with her, and then deal with the explosion of drama and insanity that happens if something doesn't go right.
Be careful with this stuff.