In order for you to play Dota 2 on Windows with minimal graphics settings, your computer must meet the following requirements
OS *:
Windows 7 or newer
Processor (CPU):
Dual core from Intel or AMD at 2.8 GHz
Memory (RAM):
4 GB RAM
Graphics Card:
NVIDIA GeForce 8600/9600GT, ATI/AMD Radeon HD2600/3600
DirectX:
Version 11
Network:
Broadband Internet connection
Storage:
60 GB available space
Sound Card:
DirectX Compatible