Is it worth replacing the motherboard of dv7t qe laptop

i have a dv7t quad edition laptop that i bought in april 2011 with the below specs

• Genuine Windows 7 Home Premium 64-bit

• 2nd generation Intel(R) Quad Core(TM) i7-2630QM (2.0 GHz, 6MB L3 Cache) w/Turbo Boost up to 2.9 GHz

• 1GB GDDR5 Radeon(TM) HD 6490M Graphics [HDMI, VGA]

• FREE Upgrade to 6GB DDR3 System Memory (2 Dimm)

• 1TB 5400RPM Hard Drive with HP ProtectSmart Hard Drive Protection

• 9-Cell Lithium-Ion Battery (over-sized) - Up to 9.5 hours of battery life +++

• 17.3" diagonal HD+ HP BrightView LED Display (1600 x 900)

• FREE Upgrade to Blu-ray player & SuperMulti DVD burner

• HP TrueVision HD Webcam with Integrated Digital Microphone and HP SimplePass Fingerprint Reader

• Intel 802.11b/g/n WLAN with Wireless Display Support


it has the graphics card ati radeon 6490m

i wanted to upgrade it to an ati radeon 6770m

i asked the hp store and they told me that i have to replace the whole motherboard
which costs about $400

but if i do my warrenty goes void which rite now is valid for two years

and i also do quite alot of gaming(crysis, halo, starcraft, warcraft, etc)

so is it worth replacing it right now or should i wait for one or two years to replace it

just from a gamers point of view