First I'd reduce your two loops to one:

  while (<DATA>)
  {
    print "$2\t=>$1\n" if /^(.*?)\s+(.*?)$/;
  }

  __DATA__
  0       5713813
  276k    CVS_RES
  264k    Desktop
  17k     Documes
  33k     SEARCH
[download]

Then I'd substitute the map for the for:

  map {print "$2\t=>$1\n" if /^(.*?)\s+(.*?)$/} <DATA>;

  __DATA__
  0       5713813
  276k    CVS_RES
  264k    Desktop
  17k     Documes
  33k     SEARCH
[download]

As long as you are okay with there being a serious loss in readability, and it smacks of golf.