I was looking for direct steps (without installing any new tools) for quite sometime and all google searches didnt yield good results, including stockoverflow.. (i used to think that no questions will go out of stockoverflow unanswered ;) ) but that Stockoverflow post gave me some tips. a vb script idea. but i found my own idea instead of that vb script.
1. Find out the number of lines on a required logfile using windows find command. find /c /v "" System.txt will give us the total number of lines on the given file.