I have Verizon 4.2.8 and the same basement and I used sn0wbreeze to jailbreak mine just fine. My wifes is also the same and jailbroken using sn0wbreeze.
I haven't even had my iPhone 4 for a week yet and am still unsure and leery about jail-breaking? I surely do not want to brick it and be left with a nice fancy apple iPhone paper weight! 