Dell Studio 1555 - Three Options

Hello,
I am Viral
I am new to this site.

I am going to buy laptop in this month..

I am going for Dell Studio 1555... thats for sure

now i am confused between three models..

Their configs are as follows..

1)
Processor : Core I5 - 520M
(2.40Ghz and 2.93@Turbo mode)
(3MB - L3Cache)
Ram : 4GB @ 1066 MHz
HDD : 320GB @ 7200RPM
Graphics : ATI 4570 - 512 MB
LCD Panel : 15.6" - 720p LED with Truelife & Camera
Sound : Creative Sound Blaster X-Fi MB
Wireless : Intel© Centrino© Advanced-N 6200
Battery : 9 Cell
=899$

2)
Processor : Core I3 - 330M
(2.13 Ghz)
(3MB cache)
Ram : 4GB @ 1066 MHz
HDD : 320GB @ 7200RPM
Graphics : Intel® HD Graphics
LCD Panel : 15.6" - 1080p High brightness - LED with Truelife & Camera
Sound : High Definition Audio 2.2
Wireless : Dell 1397 Wireless G
Battery : 6 Cell
=649$

3)
Processor : Core I3 - 330M
(2.13 Ghz)
(3MB cache)
Ram : 4GB @ 1066 MHz
HDD : 500GB @ 7200RPM
Graphics : Intel® HD Graphics
LCD Panel : 15.6" - 1080p High brightness - LED with Truelife & Camera
Sound : High Definition Audio 2.2
Wireless : Intel© Centrino© Advanced-N 6200
Battery : 9 Cell
=749$

All Windows 7 Home Premium 64 Bit


I loved the first one... but when i saw the other two i got confused...

I am Computer Eng. Student..
Usage:
Internet : much much surfing
Gaming : not crazy now... but love to play any racing game .. like most wanted.. undercover.. GRID2.. etc.. i like other games also .. like Fifa, Counter Strike, GTA etc..
Music : normal
Movies : 2-3 movies a month.. so as such not mad for them..
Technical softwares : yes, this thing i will require.. right now, i use Netbeans, Visual Studio, Eclipse, this list may increase as i become professional in my field.. so that also into consideration..
so please guide me..