NVDown V 1005

• Finally fixed downloading on Windows XP! The program will no longer crash because it can't find the folder it was being told to download files to!
• Added checks to ensure that versions of NVDA higher than 2017.3 can't be downloaded on Windows XP.

NVDown V 1000

This is the first official release of NVDown, after a very private beta test that lasted waaaaaaaaay too long!