If you are not willing to put up with possible breakage, do not use Beryl or Compiz. They are not final versions yet. If you want to use them, you might have to use unsupported (by Ubuntu) binary drivers for nVidia and ATi. Intel's open source drivers work fine. If you are not using Beryl or Compiz, you should probably stick to the open source drivers. There is a good reason for this. The developers test only for the binary drivers found in linux-restricted-modules. If you get drivers from a 3rd party source, you will have to reinstall them on every new kernel. Also, if linux-restricted-modules doesn't propagate to the server you use at the same time as the new kernel does, the drivers won't get there immediately. It is best that you check that both show up in the updates. If only the kernel shows up, don't do your updates just yet. A new kernel can break your binary graphics drivers, break Xorg, and leave you at a black screen with white "login:" text. If you are not up for fixing things through the command line, you might want to stay away from 3rd party drivers until it all works. A new Xorg is coming out over the summer. It will be in Feisty+1. It will be "bulletproof," dropping to a default low-resolution, low-depth setting if something breaks, so that there will at least a be graphical environment in which to fix it, but it won't be in Ubuntu until 7.10.
Aside from that, every time a new kernel is released, those binary drivers have to be reinstalled. You can also put the driver install file in your ~ (home) drive. Then if you have problems, you can log in at that big black screen and start typing
sudo sh NVIDIA-Linux-x86-1.0-xxxx-pkg1.run or whatever your driver is, and hit tab when you get a few letters into the installer name for it to auto-complete. That'll reinstall the driver without you having to hunt for the fix. Thanks to OffHand for the hint about keeping an installer there.