Yeah, the closest you\'re going to find to a true adventure on the PSX or PS2 is probably the Resident Evil & Silent Hill series. I have heard that there are groups waiting to make a Windows9x,3.1, & Dos emulators for the PS2 HDD once it comes out. You may want to wait for that and download a bunch of Abandonware titles like "Beneith a Steel Sky", "Hugo\'s House of Horrors", and "Manic Mansion". You can also still buy humorous Adventure titles (even if they are a bit old) from LucasArts & Sierra. I suggest the full Monkey Island series, Sam & Max, The Grim Fendago, Space Quest Anthology, Leisure Suit Larry\'s Greatest Hits (And Misses), The King\'s Quest Anthology (Or at least KQ6), and the Quest for Glory Anthology (RPG/Adventure/Action hybrid). On a console with standard hardware (Like the PS2 & Xbox) bugs like Runtime Errors and Driver incompatability can be much more easily worked out.
More serious adventure titles worth your interest are Police Quest Collection, The Indiana Jones Trillogy, and Phantasmagora. Some are still new enough that you can find them at just about any major retailer. The Longest Journey, Gabriel Knight III, Quest for Glory V, and King\'s Quest 8 are all worth checking out.
From what I\'ve heard, Shenmue for the DC is pretty close to being an adventure, so you may want to check that one out as well.