InfoPath Dev

I am fill my combo box with data from a sharepoint list.

But I'm looking for a way where by if I type a letter or two I get a filtered result of the words in the list. e.g Combobox "pi" results "pinch, pino, pinnock".

please help I'm failing to find anything or is there a type ahead way i can do.

use a drop down list box instead of the combo box

 Thanks for the reply

 but then the list is too long. how can I shorten the time of scrolling down a drop down list box?? is there a way where while the person is typing only the items he/she is typing shows e.g "b" and only items with be show??.

Thanks Again