Um...are you sure you didn't mean a PNG? (closest thing I can find on your extension was PNG. Could also be PY files, but those are python scripts)
BF2 PNGs are sneaky buggers. Sometimes they are actually in PNG format other times they are in DDS format but with the PNG extension. Try opening them with the same app you use to open/edit DDS files. You may need to try changing them to DDS extension first. Rule of thumb is, if the PNG fails to show anything in Windows's Preview tool or has no thumbnail, then it is a DDS file and not a true PNG file.
If however you meant the PY files which are python scripts, then your looking in the wrong place. Python scripts do effect mods in some ways but "most" standard modding is not done with PY files. It's in con files just like BF42. Just that they are packed in ZIP files instead of RFA files.

(also note the "tweak" files. They are also CON file type files. Just BF2's odd form of organization. Some basic code is in the CON files and the rest are in Tweak files)