I responded to your PM and thought I would come look at your post. I don't think she's a leghorn, at least she doesn't look like my leghorn in comb size or body type (other than a fairly upright tail). This picture is from a few months ago, but you can see how she has the characteristic large, floppy comb; fairly long legs; and compact body (she's a little puffed up in the first picture, so her body looks larger than it is). In the second picture she is the one with her head in the bowl, my BR is the other, larger barred bird.
Edited to add: She is also the same bird as in my avatar. That gives a much better picture of her body-type.
I'd go with barred leghorn, I know there's another name for it tho, I just can't remember, its something like an Exucutor leghorn or something. I know there's a type of leghorn that has kind of black spots on it, the name starts with an E.
i got two hens from ideal hatchery and the look somewhat like her except they have a larger comb that falls to the side, i first thought they were barred leghorns but they actually have a breed called a production black, for some reason production blacks are barred, the reason i know that they are this breed is because they don't carry barred leghorns, they lay white eggs!
She is certainly "producing." We had her about 10 days before she felt at home and laid her first egg on 1/3/09. Since then, she has only missed one day! Assuming she's a Production Black, we're really pleased with her personality.