You can also open the people app and then hit the search button to search through contacts.
Also, if this helps, you can select people that you call often as favorite contacts (go into People, go the the favorite contacts - the icon with the heart on the bottom - press Menu, Add Favorite, and select the contacts that you want), and then, with the HTC People widget, have a one-touch call (or you can add a person as an icon to a home screen and be able to call them with one touch), or, when you call up the phone, there is an icon on the bottom for your favorite contacts.
There are probably other ways that I have not yet discovered.