Rapitus SAMxS, Atmel Studio 7 and Windows 8

Other than it taking a long time to open the first time after each PC reboot, I have always found Atmel Studio to be an excellent environment to work in. Although I would not be surprised if it didn’t support older Windows versions.

If you are looking for an open source options then PlatfromIO, VSCode and Eclipse are all viable options that run on Linux. Your biggest headache is then likely to be the debug interface.