The best 8x8 sites, imho, are (in my order):
http://www.littlegolem.net/jsp/http://brainking.com/en/GameListhttp://www.jijbent.nl/http://www.itsyourturn.com/You'll see they have many players in 8x8. Yes you should play, if you're good at 7x6 you'll master 8x8 in no time, it's much easier imo. I got just about perfect at it in like 1 month (with a perfect player teaching me). There are probably about 15 perfect 8x8 players, some of whom are kurnik players (jedrek, julien, metaldragon).
P.S. ah someone else has that name at kurnik then, coincidence because he has a good record at connect four as well.
From your picture I've deduced that your kurnik name is _shockwave_ and your name is Kasia, hehe. You are on my contacts list, go to kurnik sometime play the tourneys, which still have good players like christopher, snowblind, konstodane, sangfugl, imab, jerome, and others.