Visiting professor's office before being admitted to PhD program? I have applied to graduate school (EE) and am currently at one of the schools to which I applied to. Is it a bad move if I go to a professor's office and express my interest to work with her, and show her my relevant skills?

Why I think this is a good idea:

I am an engineering physics major applying to electrical engineering. I applied to the niche areas of EE that are a good fit coming from applied physics (electromagnetics and solid state devices), but regardless, coming from outside of EE will give a bad impression to the admissions committee. So I want to do whatever possible to show that I'm qualified.

Moreover, the professor I'm interested in works on computational electromagnetics, and if I can show her that I have the required preparation, maybe she'll be more willing to look into my application through the graduate application system.

So what do you guys think? Thanks.
It sounds like an excellent idea.  I like to meet with prospective students, especially ones from atypical backgrounds; a meeting gives both applicant and faculty a chance to gauge whether someone will be a good fit for the program.

However, don't get too pushy.  Keep the conversation casual, and don't put on an elaborate show of your knowledge.  The best approach may be to ask about the professor's research, and express how it tied into what you already learned and found interesting, as well as what you are interested in studying further in the future.