Hi,
Assuming that you're using the SD Card as a HDD is this what you're trying to do?
Looking online the laptop has USB ports so you should be able to load the XP installer on a USB drive and then boot from it to load the SD card.
Use Rufus to create a bootable USB drive for the install ISO and then change the boot order in BIOS to boot from the USB if the option is there.
Given the low amount of ram (according to [https://www.zdnet.com/product/dell-latitude-x200-pentium-iii-m-800mhz-256mb-ram-32gb-hdd-xp-pro/|this] max ram is only 640MB?) it may not work too well anyway