Actually you use 16 resistors to form an R2R ladder network, it's a very standard configuration, and MicroChip even have an application note detailing it.
Interestingly enough, the current issue of EPE Magazine (Oct 05) has just such a PIC D2A, used to play back WAV files from an EEPROM, with the 24LC512 giving about six seconds of audio sampled at 11025Hz. The actual sampling is done on a PC, and the file transferred via RS232.