Firmware Ver. 1.8A with Winflash that really works in XP, so I hope it helps you solve your Firmware update problem.
The following files are found inside the driver download file.
|fw18a_05w/WINFLASH.INF||13 bytes||27 Feb 2001|
|fw18a_05w/WINFLASH.DAT||3.2 KB||7 Aug 2002|
|fw18a_05w/R18A_X5.cip||526.3 KB||17 Feb 2001|
|fw18a_05w/WinFlash.exe||450.6 KB||14 Jun 2002|
|fw18a_05w/M14A0Bck.cip||526.3 KB||14 Sep 2004|