Your feeling is correct - re-parsing the file every X ms is indeed wrong.

Although I've never tried it, I assume the File::Tail module should work on Win32. If not, you can use tell to get the position in the file when you finish one read, then seek to that position and continue from there on the next - just be sure that the position you record is one byte past the last newline in the file, since you could hit EOF in mid-line if the file is being written to as you read it.