problem with new kernel and nvidia

[Salvatore Cresce]

hello! i've installed the new kernel 2.6.30.x (i tried with 2.6.31) in
this site: kernel.ubuntu.com.
i've downloaded the right packages and correctly installed them. so i
have rebooted the system but at the end i found problems with nvidia
driver! ubuntu started in low-graphic mode... what should i do to
install a newer kernel?
P.S.: i have ubuntu jaunty jackalope,32bit.