There's no official list so far. For reported testing purposes any computer is good. The game will be optimized based on that information. You can play with the game settings for better performance, but don't tweak Windows or the drivers to fix any issues. Report and leave the fixing to HT.
As for what you'd need for an enjoyable gameplay in the Beta, some hints have been given.
First, what HiTech uses for developing the game is: Intel Core2Duo E8400, Nvidia GeForce GTX 660, 4 GB of RAM, Win7 64 bit. That's four (GPU) to eight (CPU) years old hardware.
Second, what Skuzzy has said for: CPU @ 3 GHz or more, 1 GB or more of video card RAM, GeForce 9800 GTX or better (that's about the minimum for GPU).
Third, what is common knowledge in building a good yet affordable gaming computer for most games played on a single 1920x1080 monitor @ 60 Hz: Intel multi core CPU @ 3.5 GHz, Nvidia GeForce 970, 8 GB of RAM.