Can anyone tell me a good laptop battery supplier?

[ETC]

Hiya im buying a secondhand NetBook for travelling with and I will need a new battery

Its a Vaio P13GH/Q

http://www.sonystyle.com.hk/ss/product/vaio/vgn_p13gh_q.jsp

Can anyone give me an idea of a good place to get a battery without getting my eyes ripped out, also some people say I need I do something to the bios to make certain battery's work on this (oem's) can anyone explain why and how I would do this

Cheers fellas