Oldboy is the second of a revenge trilogy by Park Chan-Wook. It's not a trilogy in the sense that they have the same characters, its just a trilogy of the same type of film (and often the same actors are recycled for each movie).
The first in the series is "Sympathy for Mr.Vengeance" and the third in the trilogy is "Sympathy for Lady Vengeance" (each title slightly different in each country).
In my opinion Lady Vengeance is the weakest of the three and Oldboy is clearly the best of the three.
Yeah that search button is stupid and has never worked for me, but why dont you just type seach.php into the url?
http://www.horror.com/forum/showthre...ghlight=oldboy