Which game is this 2D character sprite in a battle stance from?

She's Vice, capcomesque version. http://gaming.wikia.com/wiki/Vice

Adrian is right: It's Vice from King of Fighters (link)

King of Fighters was originally neogeo, though they've actually done a few crossovers with more conventional capcom games. It holds a special place in my heart for being the only fighting game series that I was actually really good at.

One of my fondest arcade memories was walking into an arcade that had just had a brand new KoF v Capcom machine delivered, and completely pwning all these kids who'd never even seen a neogeo. Played 5 games without losing a single round, got a buzz on my (at the time sexy and modern) pager, passed my game to some kid, and walked out a legend.