She was born to a politically activist family. Both of her parents are socialists. At age 15 she was discovered by a modeling talent scout (she stands about 6 foot tall), and she began a successful modeling career in England and France. Two years later she chose to pursue an interest in acting.

She debuted in the film Welcome to the Terra Dome as Jodie, then had a role in the movie In the Name of the Father (1993). Her first significant acting role was as an ambitious somewhat self-hating Irish lass in Circle of Friends (1995), which included Colin Firth and Minnie Driver. Subsequently she appeared in Hotel de Love. Since then she has acted in numerous other films, including a number of less-celebrated movies and a few flops.

In 1998 she was apparently fired from Woody Allen's film Celebrity for being insufficiently vulgar.

During 1999 she appeared in the sci-fi Wing Commander (1999), the thriller Deep Blue Sea, and The Loss of Sexual Innocence. The following year she played a role in Miss Julie and Timecode. In 2001 she had a part in Enigma, and in 2004 she played the part of Andromache in the big-budget movie Troy.

On 30 October 2005 she appeared on stage at the Old Vic theatre in London in the one-night play Night Sky alongside Christopher Eccleston, Bruno Langley, David Warner, Navin Chowdhry and David Baddiel.

In the past she has dated Mike Figgis and was engaged to Alan Cumming. She is currently the partner of the acclaimed Irish actress Fiona Shaw, and they reside in London.