Do you have to upgrade PC to play battlefield 3

it all depends on if you meet these system specifications

• OS: Windows Vista or Windows 7
• Processor: Core 2 Duo 2.4 GHz or Althon X2 2.7 GHz
• RAM: 2GB
• Graphic card: DirectX 10 or 11 compatible Nvidia or AMD ATI card, ATI Radeon 3870 or higher, Nvidia GeForce 8800 GT or higher.
• Graphics card memory: 512 MB
• Sound card: DirectX compatibl sound card
• Hard drive: 15 GB for disc version or 10 GB for digital version