I'd love to tell you something about your SB, but without your maindeck, I've absolutely no clue what to add or to remove.

My current SB looks like this, without any Legacy nonsense (Engineered Plague is sooo 2004)
// Sideboard
4 Xantid Swarm
4 Viridian Shaman (none main, obv)
4 Leyline of the Void
3 Umezawa's Jitte
Swarm against Drain.dec (obv), Shamans against MUD/Stax/your favourite Chalice.dec (another obv), Leyline against Ichorid and Long (third obv) and Jitte against everything you either want to stretch the manacurve or you need some extra antiaggro power against.
My 2 eurocent