DELL INSPIRON 6400 Upgrading Wifi mini card Help Please.

I have a Dell Inspiron 6400, and have just upgraded to Windows 7. It is 3 years old but still work well and I like it alot.

Also I now have a N Draft Wifi network, I have installed the original a/g mini wifi card, and have bought an Intel Wifi link 5300.

Before I installed it I did download the up to date software from the Intel website.

I then went to install the new mini card,Switched off and removed the battery, took out the keyboard unplugged the two antennas (one white,one black in colour), The new intel card has three antenna ports but I had read that I could still use it connecting the antennas to 2 and 3 antenna ports. I connected the white antenna to port 2 and the black antenna to the 3 port. Started up the laptop, no wifi light on the laptop and it was switched on, also it did find the software but didnt load properly. Switched off again and took out mini card and refitted plugging white antenna into port one and black antenna into port 2, switched back on laptop checking wifi was switched on, light did flash but kept flashing with 5 to 10 second break between flashes. Still nothing so reinstalled original mini card and it worked straight awau.

So my questions are:
1. Will this card work in my machine.
2. If it wont work can you recommend one that will (must be N draft)
3.If it will work what am I doing wrong, and which antenna should be plugged where etc.

Thanks for all your help. any questions pls ask away.