You did the removal process the wrong way -- with haste
GRUB stores some files, along with it's configuration file, to the /boot of your Linux installation. In Ubuntu's case, if you did a regular install (and not manual partitioning), /boot resides in the same partition as /root does. Anyway you seem to have formatted /boot (along with the others), destroying GRUB's configuration files. Without them it doesn't work, so what you get is error 17 (don't get me wrong; I don't know what number 17 actually means, but obviously it's caused by this -- check GRUB website for more information).
Solution: either reinstall Windows XP's bootloader or reinstall GRUB or some other Linux bootloader (easiest done if you just install some Linux distribution, it comes along) or install some 3rd-party bootloader.
Windows XP bootloader: boot into recovery console, using the XP setup disc. Choose, when asked, the harddisk where your XP is installed, and run
and possibly
to try and recover the bootloader. The first command warns you, but you don't have much choise but to go ahead. There is a little more documentation at Microsoft's website about these.
GRUB-installation: if you don't want to install a whole Linux-based operating system, you'll need at least a /boot partition, then a live-cd distribution (or equivalent, so you can boot your machine) and once booted, run
grub-install for the harddisk you're booting from (i.e. for the first harddisk it's hd(0,0) for GRUB), followed by
grub-update if you like. Then open
/boot/grub/menu.lst with a text-editor, as root, and make sure it includes your Windows' (and other OS') boot information.
Other bootloader installation: depends on the choice. Search using any search engine on the web.
