Here are the DiRT 3 System Requirements (Minimum)
CPU: AMD Athlon™ 64 X2 2.8 GHz, Intel Pentium® D 2.8 GHz
RAM: 2 GB
OS: Microsoft Windows XP, Vista or Windows 7
VIDEO CARD: AMD Radeon™ HD 2000 256 MB, NVIDIA® GeForce® 8000 Series 256 MB
PIXEL SHADER: 3.0
VERTEX SHADER: 3.0
SOUND CARD: Yes
FREE DISK SPACE: 15 GB
DEDICATED VIDEO RAM: 256 MB
DiRT 3 Recommended Requirements
CPU: AMD Phenom™ II or Intel® Core™ i7
RAM: 3 GB
OS: Windows Vista® or Windows® 7
VIDEO CARD: AMD Radeon™ HD 6000 Series
PIXEL SHADER: 5.0
VERTEX SHADER: 5.0
SOUND CARD: Yes
FREE DISK SPACE: 15 GB
DEDICATED VIDEO RAM: 512 MB
Dual core minim