You don't want the Splinter Cell Trilogy, believe me. I had it on PS3 and it was a total glitch-fest that Ubisoft obviously just slapped together for some quick cash. It didn't even have an inverted control option the first three months and then when Ubisoft finally patched it in, they didn't even bother to fix any of the other issues (some of which are actually game-breaking). You're better off just buying the original XBOX versions.
You have it already... Xbox versions are way better then that junk trilogy. It was bad and ugly. Even Chaos Theory was a mess with worst voice acting added and sound glitches, music loops never ended. Most people I know stopped playing it at that one.
Apparently Ubi will be releasing another one... Hope it's well done and has Double Agent "Xbox version"