Do you know how to partion a hard drive? Are you positive about using Ubuntu? If you answered "no" to either use a virtual box until you can answer "yes" to both.
If you would like to install it ON TOP of Windows: Install a virtual machine program (ex. Virtualbox, VMware) Install Linux inside of virtual machine Install it along side (or overwrite) Windows: Reboot computer with Linux install CD/DVD in the disk drive and follow the instructions.
Yes. There is a Linux port of Virtualbox and it runs Windows as well as any version of VB.
Yes, install Windows first, then whichever distribution of Linux you want second.
You can run a virtual machine under WIN7 and run whatever OS you might need to satisfy Borderlands. Start-->All Programs-->Windows Virtual PC-->Windows Virtual PC or Windows XP Mode. I have several versions of Linux running as virtual machines on my install in addition to WINXP.
Windows is better for desktop computers. Linux is better for servers.
Yes, CA-dBFast works under Linux Wine program, Although, it would be better under a Virtual Machine running Windows.
Yes Ubuntu-linux offers the "install along side windows" option.
You don't, it's a Microsoft product that runs on the Windows family. You could run Windows in a virtual machine, I suppose, but that would be of limited use.
Linux
You can't. You could run it on a Linux virtual machine inside windows though.
Yes.
If you configure the server correctly, it should work. You could always run Linux in a virtual machine, and install it there. The best route is probably to just install Linux straight onto your machine, though. You don't have to wipe Vista to do that -- Google "dual booting".