where can i get an operating system?

i have a computer that had a really bad video driver (i mean so bad it was 4-bit color) so i decided to try and fix it, what i did was i hooked up the bad hdd and my laptop hdd to my mac. then i erased everything on the bad one and put all the stuff from the good hdds "system" partition and moved it into the bad hdd, when i try to use it, it says i/o disk error or something and it tells me to replace the disk and hit a key. so i need to know where i can get a windows xp operating system but NOT an upgrade disk. i can not use an upgrade disk. so i need a file or something that i can use that i open it up and i put the files in my empty hdd. if you can help please either answer below or email me at micmac253@yahoo.com thank you