FYI, the FoxMarks sync tool for Safari is a memory hog and can cause problems. It's all python scripts, wants to run at all times, it's far from lightweight. They have one for IE (yeah, I know IE sucks) and it's just about as bad. Maybe the foxmarks (now they are calling themselves xmarks) will get this worked out, but right now I don't think it's workable except in firefox.
Oh and to chime in on the browser choice... I too use FF3 still. I really like the speed of Safari and I like the tabs/titlebar hybrid of Safari 4 beta, but it's hard to use without the password sync from foxmarks, since I still always have to open up Firefox to login to sites. :P