For gaming, I'm going to go with the G71GX. Even though its a dual core, you don't see games demanding more currently even though they are starting to use more than 2. But speed is more of a factor than cores, so if you have a quad core that only ramps up to 2ghz using more than 1 core, then you're doing better for the CPU the game is using on a 2.53ghz CPU.
But gaming is usually dependent on the GPU. You can see here, the 260M is 2 tiers higher than the 5730.
http://www.tomshardware.com/reviews/best-graphics-card,...
Now this is a double edge sword, but the 260m will be running a resolution of 1440x900. The 5730m is only 1366x768. So the extra power the 260m offers will be used to calculate the extra pixels. But more pixels will have a better looking picture.
Add up the better GPU with the faster (though dual core) CPU and higher screen resolution, I'd go for the G71GX. If you want this laptop to last as long as possible, then the extra cores might get it a little more life, but my choice is the cheaper of the two. Being a recertified, the warranty is only 90 days, so if that's important to you, then get the ncix laptop. It should still do decent in gaming.