Medium display diagonal TVs that have been on the market for more than two years have high frequency rates of between 50Hz and 1,600Hz. The KDL-50W805 has one of the faster high frequency rates (400 hertz) amongst similar spec TVs of this age.
Other 400Hz refresh rate TVs currently available which you might want to consider include the LG 47LM669s which has better reviews.
If this Sony TV high frequency rate is not fast enough for you then you might want to consider the Samsung UE40H7000 (£599) (600Hz) which also has a higher rating.
What does "high frequency rate" mean?