Retrieve all fields of activities

Hi,

I am using CRM 4 and developing a windows application in which I need to retrieve all open activities. I am querying activitypointer entity but I am not getting all the desired fields like activitytypecodename, prioritycodename, regardingobjectidname, tec. Is there any way to get all the attributes of an activity along with their id and name?

Thanks,

Kshitiz