Is that part of the window? We are doing the same woodwork throughout our house.

Is what a part of the window? What do you mean by "that"? If you mean the bead molding below the window, no, it's not part of the window, it's part of the trim.

Bumping back up in the hopes that soonermagic is still around and sees this post.

Lisa, I don't think it's a stool with a bead attached. (sill = the exterior part, stool = the interior board we refer to, inexplicably, as a sill)

I think it's more likely a "false front" stool and trim that were applied onto a more modern window unit that had no stool to begin with, like this:

Alternately, it's just a fancily routered stool a la this.

In any case it would be easy enough for a good carpenter to copy if you show them a pic.

I agree with circus. How about a half-round molding, air-nailed to front edge of bottom casing? With short matching pieces mitered to the sides?

Yeah, looking back at the photo, I suspect they did something like this to what was a basic trimless casement frame - but they lowered the stool just a tad to create the extra reveal, and left the same little reveal all around the casing:

Thanks, circus! That's how I thought it would be done but hubby wasn't so sure (ha, I'm right, woo hoo!). I'm going to show him that pic. Thank you, thank you, I'm so glad to know we don't have to remove the inner molding around the window. One less step is a good thing.

And thanks for explaining the terms. Guess I ought to know them so that I can explain things the right way. Thingamabob and whatchamacallit only get me so far.

Angie, we're using the same trim piece we're using at the top of the frame with a 1x below it. It's about the size of a half round but it's more square, very similar to the trim used around our front door because we're trying to mimic its trim details as much as possible for a cohesive look.