Split your coins in several addresses.
Sanboxie might be simplier and faster to set up.. but security-wise it is pretty weak.
A huge amount of exploits have been found in 2013. Since then a lot of improvements have been done.
But i wouldn't rely on the 'features' of sandboxie. VM's would definetly be safer.
You can read more about the vulnerabilities/attacks on sandboxie here: https://bromiumlabs.files.wordpress.com/2013/07/application_sandboxes_a_pen_tester_s_perspective2.pdf
But you should always keep in mind that a PC connected to the internet is never a safe way to store your coins.
You should only store an amount on your hot wallet PC which you can afford to lose.