[nath]

Toughie.
I think if you are going to raise the flop you have to raise a little more. A raise should be enough to show him you're serious about playing this hand-- as is, it looks like you are setting yourself up to be able to fold with a healthy amount of chips.

If you just want to call and re-evaluate on the turn, that's cool too.

I'd like to think I go ahead and call, since I'm getting substantial odds and may have the best hand (or a draw to one). Of course, after the fact it's much easier to say.

I played a similar hand recently and ended up folding. Still not sure about my decision. I think the major concern is this: does he have you beat both ways? (i.e. a higher pocket pair or a 9 that outkicks yours as well as a better flush draw). I think probably not, but only because there aren't too many hands like that that I think play like this. (Ac9x and Kc9x are the most likely, I'd say.)

If you have the pair you're ahead and it's a good call. If you have the flush draw, you are better than 2.4 to 1 to make it (as well as a two pair or trips that might win), so call.
Outside chance he has a made flush, but it's pretty rare.