Here are the Devil May Cry 4 System Requirements (Minimum)
CPU: Pentium 4 3.0 GHz or better
CPU SPEED: 3 GHz
RAM: 512MB (Windows XP), 1GB (Windows Vista)
VIDEO CARD: GeForce 6600 with 256MB of VRAM (Shader Model 3 Required)
TOTAL VIDEO RAM: 256 MB
PIXEL SHADER: 3.0
VERTEX SHADER: 3.0
3D: Yes
HARDWARE T&L: Yes
OS: Windows XP/Vista
FREE DISK SPACE: 8 GB
SOUND CARD: Yes

Devil May Cry 4 Recommended Requirements
CPU: Intel Core 2 Duo
RAM: 1GB (Windows XP), (2GB pre Windows Vista)
VIDEO CARD: GeForce 8600 with 512MB of VRAM
TOTAL VIDEO RAM: 512 MB
PIXEL SHADER: 4.0
VERTEX SHADER: 4.0
3D: Yes
HARDWARE T&L: Yes
OS: Windows Vista
FREE DISK SPACE: 8 GB
SOUND CARD: Yes