What Optifine version should I use for my minecraft?

I use the Toshiba Portégé M900. Here are the specs:

• Processor Intel® Core™ i5-520M Processor (2.40 GHz, Cache 3 MB)

• Chipset Intel HM55

• Memory 4 GB DDR3 SDRAM PC-8500, Max. Memory 8 GB (2 DIMMs)

• Video NVIDIA GeForce G310M 512 MB

• Display 13.3" WXGA TFT, Max. Resolution 1280 x 800

• Hard Drive 500 GB Serial ATA 5400 RPM

• Networking Integrated

• Network Speed 10 / 100 Mbps

• Wireless Network Integrated

• Wireless Network Protocol IEEE 802.11b, IEEE 802.11g, IEEE 802.11n

• O/S Microsoft Windows 7 Home Premium

• Battery Rechargeable Lithium-ion Battery

• Dimension (WHD) 317 x 38.2 x 230.6 mm

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