At that resolution you will be able to play it.
Also, if you were to upgrade your CPU it will help too.
Here is the minimum specs for witcher 2:
OS: Windows XP/Vista/7
Processor: Intel 2.2 GHz Dual-Core or AMD 2.5 GHz Dual-Core
Memory: 1.5 GB (Win XP), 2GB (Win Vista/Win 7)
Graphics: GeForce 8800 (512 MB) or Radeon HD3850 (512 MB)
Hard Drive: 16GB