Lpc2000

I'm looking for routines that enables my lpc2129 to safely read 
a .hex data file through the serial port into temporary RAM. Any 
ideas or code examples?

Although the LPCs operate at high frequencies, I'm a bit concerened 
about just sending hex data just like an ordinary ASCII string 
because of possible problems which can cause data loss...for 
example, reading 1 ASCII value into memory too slowly between uart 
(RDA) interrupts. What's the best way of avoiding this possible 
situation?

thanks in advance,
Leighton