I didn't know how deep the worm infected it so i decided to erase the partition. At that moment i didn't have the fdisk and format tool, so i did all that using the Windows installation.
Erased the partition just fine, created it and then formatted using NTFS file system in quick mode. Everything was going fine then something cought my attention. Before the Windows XP start up screen appeared (the one that has a progress bar) another progress bar showed up, this one was a "DOS style progress bar", but as the Windows XP usual start up screen then appeared i didn't take too much importance to that.
The real problem came after that. The thing is that it took like one minute and a half to show the desktop. After it loaded i rebootted but the same thing happened.
I have no idea what's the problem because at that moment there was nothing else to load but the OS.
Thanks in advance.