|Might depend on who 'they' are that told you it would work. If the drivers weren't designed for XP you may need to play around with the settings to get them to work.|
Other than that, did you install the driver correctly? Are the plotter and cable known to be good. Is the port configured correctly (if applicable)? Is any additional software required? If you have more than one printing device maybe you need to select the plotter before you can use it.