24 fps and Final Cut Express

I know that Final Cut Express doesn't edit native 24 fps footage. However, I was wondering what is going on when I take 24 fps footage and convert it to AIC for import into FCE. This is my normal workflow, no matter what frame rate I shot the footage in. It just so happens that my last project was shot at 24 fps. After using MPEG Streamclip to batch convert the video files (from a Canon 550D) to AIC and importing them into FCE, the item properties for each clip show a vid rate of 23.98. Doesn't this frame rate get "adjusted" by FCE when rendered? Just curious. But it's important, especially when I need to set up project properties for LiveType. What settings should I be using? Custom? Thanks.