Install windows XP step by step
Insert the original windows CD in the CD drive when your computer starting boot from your CD press any key to start installation before booting to the old windows
Now you will press F8 function key to agree the term of Microsoft windows.
Now you will starting to format the old version of on your drive C, please be sure that you select the C driver which containing the old windows files
Now you will create your operating system partition click on the empty space and write the size you need for your operating system .
Pleas note: to make your operating system 10 G.B you will write the size like that 10000