If you're looking for other rulesets that do a good job of letting you run a 'landed noble' game; I heartily recommend the d20 Game of Thrones RPG from GOO. It has the best system for running noble (or even royal) NPCs I've ever encountered (giving various levels of nobility an ECL penalty) as well as offering a great system for noble wealth and influence. Apart from all of that, it redefines a couple of the core classes into more sensible (and very playable) classes.
All around, it's my favorite non-FR book, and it's made using d20 rules.
How can life be so bountiful, providing such sublime rewards for mediocrity? -Umberto Ecco