Kernel Questions
 

Can anyone explain this line?
kernel /boot/vmlinuz vga=791 root = /dev/sda2 ro

I am complete noob to this.

Also,I am intending to triple boot win, ubuntu and backtrack. The webpage below tells me to delete all partition. What should I do if I have data in my windows. Do I have to delete and reinstall it?

http://thetazzone.com/blog/triple-bo...u/#comment-590

See this. You may also want to read the GRUB documentation.

If you have no free (i.e. unpartitioned) space on your disk, then you'll need to resize existing partitions to create space for the new ones. You can use, e.g. GParted to do this. It's probably wise to back up your data before resizing partitions, just in case.

Normally you shouldn't have to care about something like that, just because you always should have a backup of your important data. If not than that data can't be important for you.

This means that the bootloader starts the kernel named vmlinuz in the /boot directory and passes the kernel-options vga=791 (set the resolution for booting to 1024x768x24), root=/dev/sda2 (tells the kernel where the system partition, named /, is) and ro (start in read-only mode) to the kernel.