Hi Mike:
Fear not, its not a serious situation , the driver simply didnt load. Im not sure why. Did your install tell you to reboot after installing?
I doubt very much you have the driver installed. First, this is a 32 bit XP, right? 64 bit wont work..
If it is 32 bit...
Open your control panel, select add hardware and after it searches, pick "Yes, I have installed.". Then pick "Add new Hardware Device" form the menu. Then select "Install hardware I manually select". Then select "Show all devices"
Select Have Disk... Browse to the folder with the files Darwin.sys and darwin.inf in it. Select Darwin.inf and press OK.. it should load the driver that way or give you an error. THEN REBOOT if it loads. Do not attempt to run MAch4 or you will crash. If the driver loads you need a reboot if its the first time youve loaded
mach3 or darwin on this machine. If youve run mach3 with a printer port, no reboot is required..
Art