I generally don't take notes as outside of 4kp games I play mainly MTT on Pokerstars where you rarely see the same player twice. The software I use reads the hand history saved for the site and lets me know how many hands I have played at the same table as individual players and if it's more than the hands played in the tourny I'm in I can look at the history.
In 4kp games because we play regularly I have got use to individual styles and althought they do change some habits are hard to change.
Team UK Winners Full Tilt Poker Team Cup III
Individual Winner PKR Cup III