Here are the Battlefield 4 System Requirements (Minimum)
CPU: Intel Core 2 Duo 2.4 GHz, AMD Athlon X2 2.8 GHz or better
CPU SPEED: Info
RAM: 4 GB
VIDEO CARD: 512 MB AMD Radeon HD 3870 / NVIDIA GeForce 8800 GT or better
DEDICATED VIDEO RAM: 512 MB
PIXEL SHADER: 4.0
VERTEX SHADER: 4.0
OS: Windows Vista SP2 32-Bit (with KB971512 System Update)
FREE DISK SPACE: 30 GB

Battlefield 4 Recommended Requirements
CPU: AMD Six-core CPU, Intel quad-core CPU or better
CPU SPEED: Info
RAM: 8 GB
VIDEO CARD: 3 GB AMD Radeon HD 7870 / NVIDIA Geforce GTX 660 or better
DEDICATED VIDEO RAM: 3 GB
PIXEL SHADER: 5.0
VERTEX SHADER: 5.0
OS: Windows 8 64-Bit
FREE DISK SPACE: 30 GB