Soji; you're not going to find much death metal that is comparable to the examples you gave. If you want to get into deathmetal, you're going to have to be prepared to listen to something thats entirely different from what it seems that you're used to. But, uuhmmm, I dunno, the Mudvayne and Soulfly stuff is quite rhythmic and plodding, so, maybe the following death metal bands could appeal to you as a start;
Meshuggah (listen to Nothing, then work your way back through Chaosphere and Destroy Erase Improve)
Grave (later stuff; Back From The Grave, Hating Life, and again work your way back)
Deicide (Insineratehymn, Serpents of the Light, and back the way)
And if you like Slipknot, then you might like death metal with aggressive, shouty vocals;
Malevolent Creation (The Will To Kill. excellent new vocalist, and quite groovy)
Cryptopsy (And Then You'll Beg, Whisper Supremacy. Complex and heavy, but you might like those admittedly awful vocals)
and other new wave of american heavy metal bands like Lamb of God and Shadows Fall.
Ignore everyone else here; metal tends to spawn a lot of idiot elitists. I came this way by nu-metal to start as well, so I relate. =)