I had no papers at the time of application from my undergrad work and 2 presentations at my undergraduate symposia. No real conference talks or posters.
Given the option of a poster or a presentation, give the presentation. For my app, the undergrad presentations were just for show, but demonstrated that I cared about what I was doing and wanted to become proficient at more aspects of science than just lab work (ie: technician work). Letters of rec, duration, your application description of your work, and your ability to communicate and discuss your work during the interview are the most important research parts. The rest is polish. You don't need national conference talks or papers to get into even a top-ranked MSTP, although they look good and are hard evidence of your ambition.
