Thanks for your reply fowang!
Well, I have an LCD monitor (HannsG 28" - Gorgeous!) so I definitely need VSync On, it's only a question of whether to force it on through Nvidia's driver software or just use the particular game's graphics option to do so. Or both.
About the sound, it's pretty much the same question. There are 3 ways to switch from headphones to speakers (yes, I have both, sometimes I need to be quiet when my parents are around). I'm just wondering if I have to switch all 3, or just 1 (and which 1), or some combination... Which method is optimal?