I had no luck with the 4363 driver (ugly flirring patterns, no readable screen output), but the 5328 works fine for me (see my website for details, I have a full report there). I do reply however as I have the same flickering issue. That was not the case with the opensource nv driver but is unique to the nvidia: every few minutes the screen flashes once, in different time intervals. Seems a bit better when forcing nvAGP instead of agpgart, but I'm not sure about that yet.
My hardware is a Dell Inspiron 8600 with Pentium-M 1700, GeForce FX Go5650, 128 MB.