Tomb Raider Underworld Refresh Rate

Which is the best Refresh Rate for Tomb Raider Underworld
The default is set to 24
I set the game in 1920x1080+vsync+8AA(everything at maximum) and
want the best refresh rate

My Pc Specs

Case: A-Case Twin Engine BB With 3 thermaltake smart case fan II(insid
flow) and 1 arctic cooling fan (outside flow

Power Supply: Seasonic 700W 80plu

MotherBoard: Gigabyte GA-X38-DS

RAM: 4GB 2x2GB Kingston 800MHZ DDR2-NON-ECC CL5 DIMM (KVR800D2N5/2G

CPU: Intel Core 2 Quad Q660

Graphic Card: Ati Radeon HD 3870x2 hdmi 1080

Sound Card: 2/4/5.1/7.1-channel Realtek High Definition Onboar

HD c:\150GB Raptor 10.000 RPM d:\320GB WDC e:\320GB WDC (NO raid
copy/paste is the safest wa

Dvd Drive: f:\LG Sata high speed read\writ

Monitor Samsung LE40A656F1 1080p 100Hz LCD HD TV 50,000:1 connecte
HDMI<->HDM

OS Vista Ultimate sp1 64bi

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panais