Re: Transferring windows to external harddrive
First, test Ubuntu. Many users who want to test out Ubuntu will partition their drive, install Ubuntu or even make the giant leap to have it as the only OS, only to return to Windows. Download VMWare Player and install Ubuntu in there. This creates a virtual machine and you get the experience of using Ubuntu. If you then wish to continue with installing locally, continue reading.
Your best option is to partition your laptop harddrive using the Windows 7 Disk Management 'snap-in'. You'll essentially shrink your current partition enough to allow an additional partition of 20+ GB's. Then, throw in the Ubuntu CD and reboot, install Ubuntu on the newly created 20GB partition. This will put GRUB (Boot Menu) on the drive for you, allowing you to select which OS you wish to boot into.
When dual booting Windows and Linux, install Windows first. When you install Windows 7 alongside a non-microsoft OS, it won't install the Bootloader, making it impossible to boot into the other OS without a [relatively] ridiculous configuration process.
With the currently available consumer software, I doubt that you can RAID two drastically different drives (SATA/USB).
Humans are the only creatures that won't live up to the their potential. Give everything your all. When you die, die on E.
So I ask you, what do you intend to do now?