I am wondering what you mean by boot order. BIOS settings are the same whether
you are using Linux or Windows.

If you mean in the bootloader, grub, it is an easy fix. You can just edit it in
a text editor. You need to do this as root - try "sudo gedit
/boot/grub/menu.lst" from a terminal session and enter your password. From there
it is simply a matter of making the changes to the default line near the top and
saving.

If it says default 0, you can change it to the number that corresponds to the
one that you want to boot. They will be listed in order. The only tricky thing
is to count from zero, not one. For example if you want Windows to be your
default and it is the fourth OS in the list then you change it to default 3
because the first one is zero, the second is 1, etc.

More detailed instructions can be found here:
https://help.ubuntu.com/community/GrubHowto/ChangeDefaultOS