So my copy of New Vegas through Steam downloaded that large update before I got to play it, so I can't give any "before" details on that.

But my game was crashing before I could even leave Doc's house. Consistently.

I've been reading these forums for solutions and I've got the game stable.. not stable-stable, but Fallout 3 stable
So I figure I ought to contribute exactly the step I've taken so maybe it can help someone else.

1) I verified the game cache in Steam, it needed to re-download a small file.
2) I updated my Sound, Chipset, and Video drivers.
I'm running 7 Pro 64.
My PC is:
AMD Phenom II X4 945
4GB DDR2 1066 (Adata XPG Gaming series)
Gigabyte GA-MA790X-UD4P motherboard (runs the AMD 790X chipset, and Realtek HD audio)
Gigabyte GV-N26OC-896H-B (GeForce GTX 260 896MB core 216 model)
So I downloaded and installed 10.9 Catalyst chipset driver (dated 15/9... I think), the WHQL 260.89 Nvidia driver (dated 18/10), and the Realtek 2.53 HD audio driver (dated 11/10), and removed previous drivers/settings where possible before installing the new ones.

3) I then used the d3d9.dll file import trick that I'm not sure they want us to use, and screwed the permissions on the userdata\#####\#####\remote folder (I'm not going to provide instructions on either of these fixes as they're not official, appear to be frowned upon, and may/probably-will end up breaking things for future updates).

4) I also went into the Nvidia Control Panel, left all settings at their clean-install defaults, apart from Anisotropic Filtering which I set to 4x, and Antialiasing Mode which I set to "Enhance the application setting" and set to 8xQ.
Then in the Fallout New Vegas launcher I set both Anisotropic Filtering and Antialiasing to their lowest settings.

Now the game is mostly/basically/pretty much stable, and I have played around with different detail levels in the Launcher options to improve the visual quality, without extra crashing.