How can i uninstall ubuntu without installing something over top

Sure, Windows XP doesn't know what to do when it sees a linux partition on the drive. Simplest way to fix this is to grab your ubuntu boot cd and proceed to the hard drive/partition setup point. From here delete the linux partitions and save the changes. Now reboot your computer without completing the rest of the Ubuntu setup and switch back to the xp cd.

I've done this many times myself.

If you want to save a CD you can use a usb via StartUp Disk Creator in Ubuntu 9.10 System>Administration>Startup Disk Creator. Once you have a bootable cd or usb (if you want to boot from USB make sure you make it the first boot option in your bios) load up Ubuntu Live and then use Gparted System>Administration>Gparted (if you don't have it open up a terminal and type: sudo apt-get install gparted) to delete any partitions and format them to fat32 remembering to apply changes. Restart your pc putting your Win XP disk in and proceed as normal.

thank you for the advise, i don't have the boot cd, and i don't know much about this unfortunately. My cousin installed this OS on this computer years ago, now i have an XP disc i want to use. I'm not great with computers, so if anyone that can speak to me in dumb person language, i would be grateful. I copied some commands a while back from another forum, and pasted them into the directory, but had no luck, mabee i did something wrong. Anyone......thanx

For a start, are you booting from the XP CD or are you trying to mount it from Ubuntu? And what version of Ubuntu is it?

Also, give us a few details of your computer. M/b? What SP level is the XP CD? Are you using a SATA hard disk? If the latter, your problem is probably just the lack of SATA support in XP.