I personally can't confirm the 300D will shot IR, but I can confirm the 10D does and evidence indicates the 300D does as well.
Please take into account you will only be getting the Near IR portion of the spectrum. Meaning just beyond visible light.
The way to confirm you are seeing in the IR is if the green plants turn white and most everything else (like buildings and roads) retain their tone (menaing their grey value). Thus foliage goes from dark to light and eveything else pretty much stays the same.
If using the Hoya R72, everything is probably going to turn mostly red because pretty much only the red pixels are going to record. This filter does let through a little bit of visible light though so some of the Red, green and to a lesser extend blue pixels may record some light at longer exposures.