Lpc2000

Your code is not much different than mine, but I have a few more 
things in there for checking busy.

void attrib_RAM FlashVaderData(void) {
	Disable_INT();		// Disable INTs
   	// Prepare to erase
	flashParams[0] = IAP_CMD_PREPARE_SECTORS;   // prepare sector
(s)
  	flashParams[1] = CFG_FlashDataBlock_Sec;    // start sector
  	flashParams[2] = CFG_FlashDataBlock_Sec;    // end sector
   	callIAP();
	IOSET=IO_USB_ACK;	// toggle USB line
   	// Erase
	WaitTillFlashReady();
   	flashParams[0]=IAP_CMD_ERASE_SECTORS;
   	flashParams[1]=CFG_FlashDataBlock_Sec;
 	flashParams[2]=CFG_FlashDataBlock_Sec;
   	flashParams[3]=CCLK/1000;// CCLK in KHz
   	callIAP();
	IOCLR=IO_USB_ACK;	// toggle USB line
   	// Prepare to program
	WaitTillFlashReady();
   	flashParams[0]=IAP_CMD_PREPARE_SECTORS;
   	flashParams[1]=CFG_FlashDataBlock_Sec;
   	flashParams[2]=CFG_FlashDataBlock_Sec;
   	callIAP();
	IOSET=IO_USB_ACK;	// toggle USB line
  	//  Program
	WaitTillFlashReady();
   	flashParams[0]=IAP_CMD_COPY_RAM_TO_FLASH;
   	flashParams[1]=CFG_FlashDataBlock_Adr;	// Dst FLASH adr
   	flashParams[2]=CFG_RamDataBlock_Adr;	// Src RAM adr
   	flashParams[3]=1024;
   	flashParams[4]=CCLK/1000;				
	// CCLK in KHz
   	callIAP();
	IOCLR=IO_USB_ACK;	// toggle USB line
	WaitTillFlashReady();
	Enable_INT();		// Enable INTs
}

Essentially here are the 4 steps and their timing:

IAP_CMD_PREPARE_SECTORS     (<4mS)
IAP_CMD_ERASE_SECTORS       (400mS)
IAP_CMD_PREPARE_SECTORS     (<4mS)
IAP_CMD_COPY_RAM_TO_FLASH   (<8mS)

I am simply toggling a line IO_USB_ACK on the board and sampling with 
the scope.

So all of my time is spent in doing the erase task on this single 
sector - 400mSec.  That's the problem.

Why do you think yours is 100mS and mine is 400mS?

Thanks,  Chris.