>If this field allows only 2 state: Y or N you can try checkbox, as Mike suggested, but you should do some manipulations...

In some cases, the "appropriate" control isn't dependant on the data, but on the users.

A checkbox isn't always as explicit for the user as a dropdown with Yes or No. Some users get confused about what a checkbox means. (i know it's hard to believe, but there are people who still don't understand "right-click" either)

you might also use a 2 state dropdown for consistency if all the other choice fields are dropdowns, and it would look wrong to suddenly throw in a checkbox.

I've learned that you can have a killer app in every respect, but if the user doesn't "get it" because of the UI, the whole thing is sunk. (i've gotten complaints about the caption of a command button because I used the wrong word to describe the way the user thinks about a process, regardless of what the button actually does)

...just my $.02 on UI design.