Firstly MD5 is a hashing method. Aka a way to check that a file is not corrupted during download:
File on server > MD5 = 1234
File on computer > MD5 = 1478
Then file on server is NOT file on computer.
So do not worry about that TO much. If you have issues during install or something then you might consider a corupted download, but if it was downloaded one shot (not paused and resumed etc) there should not be any issues usually.
Then on to the minimal install. In my personal opinion, it is a waste of time and resources downloading a minimal image and then just installing everything manually that is included on the vanilla install disks. However if you do wish to go this route here are some of the basics you will need to get a desktop environment. I will post gnome3, so you will essentially end up with a full vanilla install of ubuntu. May I recommend a lighter release such as Xubuntu or Lubuntu? This should help with battery life a bit. Also, ubuntu is not quite laptop/notebook optimized so battery usage is somewhat higher than windows. There are a few tweaks to help, but that is all they are and do, tweaks that help.
Oka enough yada yada:
sudo apt-get install ubuntu-desktop
sudo apt-get install kubuntu-desktop
also on a CLEAN install you can try:
sudo apt-get install xubuntu-desktop
I see this is the recommended way on the download site here:
sudo apt-get install tasksel
That should cover it. But just for reference see this post:
To install, boot your computer from the the Minimal CD and type "cli" (command line install) at the prompt. You can then follow the instructions from the text-based installer. After the base system is installed, log in, and type "sudo tasksel" to select the system to install.
It is somewhat outdated but it gives you an idea of what to look for if you run into some trouble along the way.
For a quick comparison of desktop environments and shells see here: