S, I've been doing some looking around on the general issues of ATI vs. NVIDIA for linux. I'm buying a new laptop, and obviously want to maximize linux compatibility.

Here's what I've understood so far. For the people who know: is my understanding right?

ATI has open source drivers, but they're kind of spotty. Also, ATI relies on the vendors to provide drivers, so if the company selling the laptop doesn't provide linux drivers, you're out of luck.

NVIDIA doesn't have open source drivers, but their closed source drivers provide good linux support. They provide drivers directly, rather than relying on the laptop vendor, so chances of linux support are better.

Anybody else have experience/knowledge in this area? I'm looking to do things like 3D gaming, video editing, playing back HD online video, possibly even some graphics rendering if I decide to pick that up...

Most of the laptops I'm looking at either have the NVIDIA GT425M or the ATI HD5730.

Thanks!

Both, ATI and NVidia, have open source and closed source drivers, and you can download the closed source drivers directly from their website.
The free radeon-driver for AMD cards works pretty well nowadays, but the closed source driver can be somewhat spotty. I never had issues with this drivers, but have heard that from others.
The free nouveau-driver for NVidia has currently no support for 3D, but the closed source driver works pretty good.