6890 or 5850

Choosing a GPU within the next week and I adore the look of the 5850 but is there much difference in performance between the two? I mean In my own opinion I would sacrifice a little performance for the aesthetics of the 5850 as Im not going to be heavy gaming (well not yet anyway)
SPECS:
AMD ATHLON X3 (TRI CORE 3.2ghz)
4GB DDR3
Alpine 650W Silent PSU
Asus M5A78L-M LX

Budget - £140

Thanks