I3 vs custom built, less great processor?

http://www.staples.com/HP-Pavilion-dv6-2150us-Laptop-(Espresso-Black)/product-nr_848835

OR i can customize one basically.

Operating system Genuine Windows 7 Home Premium 64-bit edit
Processor Intel(R) Pentium(R) Dual-Core Mobile Processor T4400 (2.2 GHz, 1MB L2 Cache, 800MHz FSB) edit

OR it can go with Intel(R) Core(TM)2 Duo Processor T6600 (2.2GHz, 2MB L2 Cache, 800MHz FSB) not sure which is better.

Memory 4GB DDR2 System Memory (2 Dimm) edit
Hard drive 320GB 7200RPM SATA Hard Drive edit
Graphics card Intel(R) Graphics Media Accelerator 4500MHD with 5-in-1 integrated Digital Media Reader and HDMI edit
Display 15.6" diagonal High Definition HP Brightview Display (1366x768) edit
Primary optical drive LightScribe SuperMulti 8X DVD+/-RW with Double Layer Support edit
Personalization Webcam + Microphone edit
Networking Wireless 802.11b/g/n Card edit
Keyboard HP Keyboard edit
Primary battery 6 Cell Lithium Ion Battery (standard) edit
OS and recovery media System Recovery DVD with Genuine Windows 7 Home Premium 64-bit edit
Office software Microsoft(R) Works 9.0