|XP generally doesn't need boot discs (floppies). Could it be you have the boot order configured incorrectly in the BIOS?|
How about downloading the ISO to create a new WinXP CD with SP3 already slipstreamed into it? Just burn it to a disc using ImgBurn or similar software.
Here you go ---> Windows XP w/SP3 - direct download
Pay close attention during the installation of ImgBurn & don't allow any of the bundled software to install along with it.
Get it here ---> ImgBurn 18.104.22.168