I am using Win8 at the moment.
I have XP / Vista and 7 machines and this, as already stated by a few, is very different.
I may go as far to say frustrating at times ( but I am over that now ).
This is a new machine and came with the usual bloatware!
I hate it when a machine comes pre-installed with McAfee - this even had Norton as a back-up option.
One of the first things I did was to install Revo Uninstaller and get rid of them - plus other software that I didn't want or need.
I then decided to download MS Essentials - my favourite AV - to discover that Win 8 already has it installed in the form of Windows Defender.
Defender is not new and was always part of Vista and Win7 - but not in this form.
It is, as already stated, a combination of the old Defender plus Essentials. So no need to download an AV .....it is already there.
Now the frustrating part
I found the search option quite quickly and needed to enable Defender as McAfee on the system meant that the inbuilt option was disabled.
Fine - type in "Defender" into the search option and hit ENTER.
I got a message that Defender was disabled - I knew that !! I wanted to enable it but couldn't open Defender to do so !!
Quick search on line I thought ......
I found numerous options that suggested various methods - none of which worked.
( and I was online without an AV !! )
I spent a very frustrating hour or so trying to enable what should have been a simple process.
Got there in the end :)
The thing with Win8 is that the system is very different from the previous systems.
Things that were readily available in Vista seem to be hidden in Win8
I like the look of the Operating System it will, however, take some time to find out where everything is hiding.