I love Halo CE, and I have played my fair share of it. Halo 2 is pretty great too.
But I will be honest: I have never played past that, because those were the only two ported to PC. I can't play console FPSes at any reasonable skill level (I tried playing Halo CE on Xbox once, I gave up on the second level because I couldn't aim for the life of me). Something about me and dual analogue controls just don't get along. So, while I don't expect or want a Halo 4 PC port anytime soon (that thing's selling Xboxes, after all, I'd be great with waiting a few years), I'd really like to see at least a Halo 3 port. Seriously, just release that on PC and a lot of people would pay at least $30 or $40 for it, if not up to $60 (I would). Halo 1 and 2 were ported several years after their Xbox releases, and I'd be willing to bet it could sell even 5 years on! (Seriously, you'd have people like me who never played it but had played predecessors, people who had switched to PC from console gaming and wanted to re-experience it, and people who wanted to give Halo a try buying it!)
I doubt it will ever happen, but I'd like to experience the later games in a great series even 5 years after they came out. Is there anyone else who feels similarly?
(Yeah I doubt it since you've all already have played those games, but I figured the current Halo dev's site was as good a place to ask this as any)