Seems clear to me that since the OP is coming from a hip hop background and based on what he's said he already likes, he'd probably like stuff that is mostly beat driven. I'd recommend:
Deftones - White Pony or Diamond Eyes
Helmet - Meantime
The Notwist - Neon Golden
OK Go - Self titled or Oh No
Thousand Foot Krutch - Set It Off or Phenomenon
311 - Soundsystem and/or Transistor
The Heavy - Great Vengeance & Furious Fire
Death From Above 1979 - You're A Woman, I'm A Machine
The Datsuns - self titled
Beck - Guero
Kasabian - self titled
Clutch - Blast Tyrant
Weezer - Pinkerton or the Red Album
Fugazi - 13 Songs
Sublime - self titled
Dan the Automator - Music to Make Love to Your Old Lady By
Citizen Cope - Self titled
Incubus - Make Yourself or Morning View
Rollins Band - Weight or The End of Silence
Bullfrog - Self titled
Superdrag - In the Valley of Dying Stars
Filter - Short Bus
Dynamite Hack - Superfast
Pinback - self titled or Autumn of the Seraphs
Radiohead - (just about anything)
Ted Leo & The Pharmacists - Living With the Living
...that should be enough to get you started.
