Jason_the_Iguana: That's actually one of my favourite parts of the game. My character is wanting to go deal with some vampires but first Jaheira gets in trouble and then Anomen goes and does something deeply stupid and before that's over Jan rushes off to deal with a personal crisis. It can be a bit frustrating, but in a good way, because it makes the game-world feel more alive and reactive.
That very much echoes my own experience, with different NPCs.
[Spoilers follow]
Setting out following a devastating blow to the party, and my own character, to attempt to at least get Imoen back from the prison. Finding situations which are more urgent, and which my character's conscience won't allow him to delay on - Imoen is, after all, only imprisoned (so far as my character knows), and letting a town/castle die to get her back a little quicker would be wrong.... Finally getting through these and preparing to board the ship, only for a dark figure from Jahiera's past to show up and poison her...and then attempt to claim diplomatic immunity due to being unarmed and not fighting when I reach him.
Coincidentally, my own character indeed wouldn't kill someone in cold blood like that, whatever the motives - it would set a dangerous precedent for someone with his bloodline. I got around it by pointing out, in character, that while yes, I wouldn't attack someone in that way, Minsc was bound by no such requirements...
[End spoilers]
More on topic, I definitely preferred BG2. Don't assume by that that I didn't enjoy BG1: when I played them both for the first time last year, I still found it one of the best RPGs I've played - it was just vastly eclipsed by BG2 when I got to it. I'd strongly recommend playing BG1 first, preferably with the canon party. That'll allow you to enjoy what BG1 has without comparing it to BG2, and will mean you have that much more developed a character by the time of BG2, and have actually experienced the adventuring with the party which BG2 assumes. Plus, it's just...nice to go through the whole series as one story, especially the first time.