How do i remove boot loader, to be able to install windows

The bootloader will not impact the installer in any way. The OS will install and overwrite the MBR which currently contains grub2. You will simply need to tell the XP installer to remove the Linux partitions and then install.

Windows Support doesn't look very competent.
First thing a new operating system do at installation, is to overwrite current MBR with its one!
What is exactly error message ?

XP is not very sophisticated. When you install it, it will overwrite everything on the hard disk, unless you set up a separate partition and install windoze there.

I'm guessing you formatted your hard drive to ext2,3, or 4, which windoze doesn't recognize, so it's crying murder.

Try downloading gparted and add a second partition to your hard drive and format it to NTSF and install windoze on that partition. afterwards, you'll need to re-install grub from your ubuntu boot disk.

Why not try this? Go on live CD mode with UBUNTU.Access terminal and type in fdisk /mbr >enter.It will remove the Grub Boot loader.Shut down ,remove UBUNTU CD.Restart now Windows XP will be able to boot.Please note there is a space between Fdisk and /while typing this command.Please tell us how you fared.

Thanks marcus aurelius, that solved my question.

Sorry i clicked on "Answer solved" button. But it's not solved yet, i had no time to try all your suggestions. I did format it NTSF. Then i tried it unassigned. The CD itself is OK.
This is OEM Win XP, and it crashes just when it says "loading Window files". I forget what it says "error loading files, aborting" or something. It's all very terse.
Wasn't able to try anything yet, I have other problems, so everything is going slowly, i added an older HDD but couldn't access it, and found out somebody already posted the same problem, and it was never resolved. That post is 1 1/2 years old. But he found a runabout way to do it, Alt F2 and "gksudo nautilus" and it loads nautilus to root, so now i am able to transfer the files i need to keep.

kesava -- i tried <fdisk /mbr> from Live CD, and it says "unable to open /mbr"

fdisk /mbr is a Windows command, not one from Ubuntu.
Both systems have a fdisk command, but only Microsoft's one has an option /MBR.
At installation, XP should have overwritten MBR. I think issue is on XP CD. During loading, the XP installer will not use data on disk, including MBR.

I beg to agree and disagree with Olivier. Fdisk /mbr may not be from UBUNTU but it has definitely found use in Linux ,to be precise in the Redhat8 User manual.It has come handy for me to access Windows when ever a dual boot has failed due to Grub problems.In the present case Mike's NTLDR would have been seriously affected. NTLDR rescue floppy/CD can access XP .The other option use Win XP OS CD ,seek the Repair option,and Command FIXMBR,may help solve the issue.May be excused to quote this here, Launchpad being an UBUNTU discussion facility.

Either way, if you remove the partitions in the Ubuntu liveCD it will be fine. I believe the XP CD can do this too but the user cannot find the option.

XP support is dead on 8th April, 2014 so I'd recommend you grab Win7 or Vista and become accustomed to those

Soorry for the delay. I have done some testing, when i finally managed to back up my files, i installed XP on my other computer. Everything went OK. It's working, except the usual primitive aspects of Win.
So the problem on my notebook, ThinkPad, may not be on hard drive. Notebook has USB CD-ROM (the original one died), and that could cause the problem. The computer i installed it on, has internal CD-ROM.
I am soon going to try to install the XP on the notebook, and describe what happens.
There are just too many things going right now, and i don't want to lose my email access. So as soon as the other computer is on line, i will experiment with the notebook.
BTW: actionparsnip -- 2014 seems far away, i am going to worry about 2014 in 2014, besides i don't think MS is giving much support anyway.
I also heard Win 7 doesn't run the old, DOS/Win 3.xx based software anymore. So it would be "it" for my ACAD.

You can run dosbox in Win7 if you need to run DOS apps

Good Show, Mike

actionparsnip -- thanks for a good hint. I didn't know win 7 had DOS box. But i need Win 3.xx to run my CAD.
I may have to go back to SP2, the SP3 won't let me install the CAD. It says "invalid files, not win32", or something to that effect".
I had it in SP2 before, and i erased it, it was czech version, and my wife doesn't speak a word of czech, so it wasn't practical. I didn't suspect i would have all these problems getting the win back in there.

You don't need virtualbox for DOSbox, DOSbox is a separate application. You can even install Win98 in DOSbox :)