thx for the prompt feedback, guys!
still not quite sure the truth has been unveiled yet though...
i have been thinking about this one because it seems a relevant number for some preflop situations e.g. how much better the chance of winning a pot with AKs in relation to AKo?

i actually follow zenbitz's argument well and think it most likely is the correct process for doing this calculation . you seem to understand the mathematics in this very well.
though doing the calculation outlined i come up with 9.15% on my calculator. (assuming i didnt screw up somewhere on the line)
thats 0.02% (7-flush) + 0.72% (6-flush) + 8.42% (5-flush)

@bigspenda:
arent you neglecting stuff like backdoor flushes?

cheers