To get the configured Display Value of a Field in a SPListItem, use the following Code:
new SPFieldLookupValue(SelectedListItem["FIELDNAME"] as String).LookupValue
Another way would be:
SelectedListItem.GetFormattedValue("FIELDNAME")
The second snipped displays also a hyperlink to item in the lookup table (surely it must be a lookup field, otherwise just the value will be displayed).