Final Cut Express Importing Problem

I LOVE to do video editing (mainly making music videos). However, I have recently run into a couple problems.

First, I switched over to a Mac, something I have never done to date. Second, I have been using programs like Windows Movie Maker and Sony Vegas for my editing. I had become quite comfortable using Sony Vegas until I made the switch. I now have Final Cut Express and I am having some difficulties.

The biggest problem I am having is all my footage no longer works. When I go to import it into FCE, it gives me the error:

"File Error: 1 file(s) recognized, 0 access denied, 1 unknown."

I don't really understand this, but I was able to figure out that it must have something to do with the video format. I converted the file to a format which it seemed to accept. However, I can view the video in the viewer, but when I export it to the timeline and try to view it via the canvas (to see if it matches the music), it says that the video is "unrendered". Is there another video format I should be using that would enable me to view this footage with the imported music in the canvas? Or must I re-render every time I make a change (which I am sure I shouldn't have to!)? I'm very new to FCE so I do not understand it fully--keep in mind, I'm used to dealing with programs like WMM and Vegas in which rendering was the very last step you did.

I am currently using Handbrake to convert my files, so if there is a known file type that I should be using in order to properly import them into FCE, please let me know!!!

I've tried looking online for ways to fix this problem, but I can't seem to find anything that really seems to help. So any suggestions would be WONDERFUL!!

Thank you!!

Where is the source coming from and in what format?

If you convert it to DV format with audio at 48Khz than you won't have the re-rendering problem because can edit that natively. Another codec to try is Apple Intermediate Codec (AIC). There are other codecs that might be better.

The files I'm using are coming from several different sources. They range from MPEG-4 to .AVI files.

I will try the format you suggested (the AIC format) and see if that works! I'll get back and let you know! Thank you!!