If you have programs that you are running on your older Windows computer and are not interested in the new Modern (Metro) front end on Windows 8, it is absolutely not a problem.
I was leery of upgrading my XP that I was using for production, so I took an older retired XP and took advantage of the now expired $40 upgrade including a free download of Media Center and upgraded that (Run the program that checks if it is compatible with Windows 8).
It brought it back from the dead. Now a friend of mine uses it every day. Don't give up on that older system right away, there is no reason why it should die.
Even changing a Motherboard is just plugging your parts in with plugs where you can't make a mistake.
I run a Windows 7 and Windows 8 system side by side every day each with dual screens and on the Windows 8 system, I never see the Modern Front end unless I click on a key.
Desktop on Windows 8 is a slightly faster, slightly improved Windows 7 with a few nice new features including some I like for my dual screens.
You do not have to download the Classic Shell if you remember 3 things that fit on a Post-it note.
You never have to see the Modern Front end if you change a couple of defaults,
If you still use POP3 email then you will have to download your choice of a free POP3 email programs.
I use Thunderbird by Firefox.
First the Defaults:
1. Change the Photo Viewer default in Control Panel to Windows Photo Viewer
2. Use the Desktop version of Internet Explorer which is already on Windows 8
3. Boot to Desktop by using Windows 8.1 or by just automatically loading a Desktop program
I happen to use StickyNotes (that is how I found out that it did that) Otherwise just click on the Desktop Tile.
Now about the Post-it note or installing Classic Shell. Just remember three things.
1. If you mouse over to the left corner a start Icon appears, right click and you have most of your Start Button items.
2. Click on the File Folder on the quick start bar and you get File Explorer that has your documents, Music, Pictures, Videos, Computer, Disks, Network, etc.
3. To turn off you can press the off button on your computer (yes, it's ok), You can Ctl, Alt, Del and hit the power icon on the lower right, or you can mouse over to the lower left and click on settings and then the power Icon. Did it ever make sense to press Start to Shut Down?
Just three things to remember.
How about pinning programs. I pin my less used program to the Modern Front End so I don't have to search for them. You can still pin to the lower left task bar and to the Desktop itself, just like Windows 7.
You can pin all your Administrative Programs (those techie programs) to the Front End all at once by going to the right corner and bringing up Settings, Tiles and moving the slider on Administrative Programs to On.
That is it, then you can delete the ones you won't ever use and organize them on the screen as you want.
All that said, I did download the free Classic Shell to see what all the fuss was about and guess what, I love my Start Button/Menu, but you don't need it.