My current machine is running Windows 7, and I've only had to go through a full reinstall once because of my own stupidity- I was tempted by an offer into up(down?)grading to Windows 8, and I quickly came to the conclusion that it wasn't for me- my life isn't exciting enough for 'Live Tiles' and I found the entire interface to be too touchscreen-oriented for my liking. I also dislike intensely the trend in OS design towards huge fonts, childlike buttons, and simple applications and utilities taking up the whole screen for no apparent reason (apart from touchscreens, which my PC doesn't have). Good luck to those who get on with all this stuff, but I'll probably end up sitting out Windows 8 and seeing where all this goes.
One thing that is worth considering if you want to keep any new machine 'clean' is to be very careful what files you open, keep to a very limited set of core programs that you know and trust on the main operation system, and use a program like Oracle's VirtualBox (free) to create one or more virtual machines for experimentation and one-off program installations to do particular jobs. I run Windows 2000 in a VM in order to run GMax, an old version of CorelDraw and a couple of other older programs, and I've also got an Ubuntu VM to experiment with Linux apps. I find Linux to be handy for finding programs to do file conversion or low level disk tasks. I prefer not to give my VMs access to the Internet, to limit opportunities for malware. If your VM gets trashed for any reason, you can simply delete it and build another one without affecting the performance of your main OS.
Regards
R3
One thing that is worth considering if you want to keep any new machine 'clean' is to be very careful what files you open, keep to a very limited set of core programs that you know and trust on the main operation system, and use a program like Oracle's VirtualBox (free) to create one or more virtual machines for experimentation and one-off program installations to do particular jobs. I run Windows 2000 in a VM in order to run GMax, an old version of CorelDraw and a couple of other older programs, and I've also got an Ubuntu VM to experiment with Linux apps. I find Linux to be handy for finding programs to do file conversion or low level disk tasks. I prefer not to give my VMs access to the Internet, to limit opportunities for malware. If your VM gets trashed for any reason, you can simply delete it and build another one without affecting the performance of your main OS.
Regards
R3