content: Just dual boot it.  Does the warranty mention installing a second OS, or just removing Windows?  Technically, you'd just be replacing the Windows boot loader, the OS would remain intact.    Hell, you could set the GRUB timeout to 0 (hold the shift key when you want it to pause) and have it boot Windows as default; they'd probably never notice there was another OS installed, it's not like Windows will show your ext4 partitions.