Failed to setup X

[pazuzu]

Linux newb, so be patient please.
Installed Kubuntu 7.10
Installed nvidia drivers for GF440MX from nvidia website (96.43.05)
(the ones on installation cd's aren't working, setup ends abruptly, graphic environment won't load after reboot)
MCE's installation goes just fine
During installation I selected UI2 with alpha blend (test was positive), and I remember I read in the wiki GF440 could support alpha blending.

After reboot, when I hear the serie of beep I press and hold shift, but in the end I get a screen telling me "Failed to setup X"

Driver problem?
No Blending next time?
Any suggestion?
Thanks