Look at the battery you got now if it says 11.1v then the 2nd one should work, if it says 10.8V maybe not. You best ask the shop selling it realy then it's their fault if they give you bad advice
Don't worry about 4400 mAH being different the higher this number the better, it means it will hold more charge.
Laptop batteries are clomplex beast as i learned in a power cut and tried to wire one up to power a torch. Damn battery blew out and it cost me £60 for a new one. The torch was okay though, Doh!
DinoHunter (still no nVidia compo voucher!), CPU/GPU Benchmark, DarkFish Encryption DLL, War MMOG (WIP), 3D Model Viewer