running 2 os

[songamericadj]

Can ubuntu & windows be installed on the same computer?

[tuxcantfly]

yes, it's called dual booting, just install windows first, then install ubuntu, it'll shrink your windows drive and add an option to the GRUB bootloader to let you select between ubuntu and windows on bootup

[Mike_Longbow]

You can take a look at this (https://help.ubuntu.com/community/WindowsDualBoot) if you're planning to dual boot.
Altought the process is generally very straightforward. The only step you should take special care about is when it comes to split (partition) your drive.