Lpc2000

I am trying to figure out what resolution I can get from the AtoD pins 
on the LPC2292 processor.

There are significant errors as follows:

DLe Differential non-linearity - ±1 LSB
ILe Integral non-linearity - ±2 LSB
OSe Offset error - ±3 LSB
Ge Gain error - ±0.5 %
Ae Absolute error - ±4 LSB

When I calculate the cummulative error I get 5.5 LSB's.  Can this AtoD 
give 1 or 2 LSB's of error or will I need an external AtoD for anyting 
better than 4 or 5 LSB's.

Thanks