Lpc2000

I found this on the Page from Rowley.

>>I'm trying to use vectored interrupts on the LPC2000. I've 
programmed >>up the VIC but when the interrupt occurs the program 
jumps to >>the "irq_handler" label/function, not the ISR I have 
configured using >>the VIC.

>>How do I make the LPC2000 jump to my vectored ISR when the 
interrupt >>occurs? 

Answer:     
 
You need to have the instruction "ldr pc, [pc, #-0xFF0]" located at 
the IRQ exception vector for vectored interrupts to work.

To do this make sure you have the preprocessor definition 
VECTORED_IRQ_INTERRUPTS defined when you compile the 
Philips_LPC210X_Startup.s file.

This mean i have to define anything before i can use the vic?
Can anybody explain pleas.

thanks mathias