Here is the new results (made on other machines so the absolute numbers do not match).
SQL 2000 Memory CPU DURATION READS WRITES
Original 5304 670 920 13555 0
Peso 8685 125 125 604 0
Hugo 8685 110 110 604 0
SQL 2005 Memory CPU DURATION READS WRITES
Original 8838 437 558 851 0
Peso 8838 172 250 562 0
Hugo 8838 125 230 562 0
As Hugo suspected, the NOT EXISTS (double negation) is slightly faster.