need help quick(ubuntu to windows)

so my brother got pc free pretty old but has ubuntu installed and trying to install windows xp sp3 but since i have no cd i was going to install via usb but when im going though boot mode it doesnt show usb just cd floppy and network. so do i really need a cd or is there another way?

 

What is the make and model of computer? Did you go into BIOS and change the boot order so that USB Storage is ahead of the hard drive?

 

Actually I found that it counted as a hdd but even though I pit the USB to boot first it it loads for like 30mins and still nothing and it originally had XP sp2 but it's a hp dv4000 512mb ram

 

I believe XP SP3 needs 1GB of RAM to install properly.

 

No. It sure doesn't. It will run smoother with more ram but that has nothing to do with it not installing. How did you make your usb drive bootable?

 

The computer won't boot from USB? Or you just don't have a CD?

If the former, perhaps PLoP is the solution you're lookling for?
http://www.howtogeek.com/howto/16822/boot-from-a-usb-drive-even-if-your-bios-wont-let-you/

 

we got a cd and burned it and got installed works fine youtubes a little choppy but runs great. also it did boot usb but was taking a long time (30 minutes and still nothing) plus it was showing as hdd not usb in bios