Comparing 3 laptops... help please!

Comparing 3 laptops i7-720qm (quad) vs AMD Turion Ultra Dual core M620 vs Asus dual core?
Ok so I have been laptop shopping for a while now. I know what I want. I want a gaming laptop.

Some things that are important to me are dedicated memory, processor speeds, screen size.

I have found 3 that i am really interested in.

1) HP AMD turion ultra dual core m620 2.5 ghz
17.3 screen
6 gb of DDR2
640 HD (not really worried about hard drive space)
ATI Mobility Radeon HD 4650 Graphics Adapter has 1024 MB of dedicated video memory

http://www.walmart.com/ip/HP-17.3- [...] A+Exchange

2) Dell - Studio Laptop with Intel® Core™ i7 Processor i7-720QM
4 GB ddr3
17.3 in
500 GB hd
ATI raeon HD 4650 1 GB dedicated

http://www.bestbuy.com/site/Dell+- [...] Id=9718895


3) Asus G72 Best Buy version
Intel® Core™2 Duo mobile processor P8700
6 GB ddr2
NVIDIA GeForce GTX 260M graphics 1 GB dedicated

http://www.bestbuy.com/site/Asus+- [...] Id=9556125


Ok so I have 3 choices. I don't know if i7 which is a quad is better to get than the AMD or the ASUS dual core's. I have heard that for Gaming AMD is better than intel.

Also, ATI vs Nvidea I have done a little bit of research and found that there has been quite a few failures on the Nvidea.

And the DDR2 vs DDR3

Overall I would like help deciding what to choose, or if you have any other options.

As for the games that I would play, Not crazy like Crysis, but more like Heroes of Newerth//League of Legends//Starcraft 2 (When it comes out)//WoW ( don't play anymore, but I think that is a good reference)

Thanks for your input.

Jon

the first one for budget gaming has a ATI Mobility Radeon HD 5730 is that alot better than the 4650 or just marginal?