This should work both for Ubuntu 10.4 and Ubuntu 10.10.
After installing NVIDIA’s or ATI’s video card proprietary driver the graphical boot, managed by Plymouth, reverts to an ugly text-only version. To restore the graphical boot you can follow the instructions written here. Basically you just have to download a script and run it:
$ cd $ wget http://launchpadlibrarian.net/57638460/fixplymouth $ chmod +x fixplymouth $ ./fixplymouth
HINT: the script will ask you to select a video resolution. I think you’re better off with 1024×768-24, higher resolutions might not work.
Here’s what happens under the hood: the script installs uvesafb user space programs and configures Grub and some parameters for the uvesafb kernel module; finally it rebuilds the initramfs image and updates Grub2.