There are a lot of topics being opened with similar problems so I thought I'd list what got my game working again in the hope that it would help others. Please feel free to add to it. (I run an i7 875, 16gig ram, GTX 480 (overclocked) and Win7 64bit Pro but most of these suggestions should work for anyone.)

Verify your cache at online Steam (Don't sweat the 1 file download thing.)

Update all your drivers. (Video, audio, keyboard, mouse and any gaming devices.)

De-frag and optimize your hard drive.

Run a diagnostic utility (System Mechanic, whatever, there's a bunch of them out there) to clean up your Windows Registry etc., often, because FONV dirties it.

If you use an iNvidia card - http://www.geforce.com/Optimize/Guides/new-vegas-tweak-guide - not just the tweak guide but the two Optimize choices in the upper left hand corner.

Download and install FOMM - http://www.newvegasnexus.com/downloads/file.php?id=36901 - although some people have been having problems with this since the 1.4 patch.

Download and install fnv4gb NVSE - http://nvse.silverlo...fnv4gb_nvse.zip - to your SteamApps\common\fallout new vegas\ folder, make a shortcut to you desktop and launch the game from the shortcut (if you run a 64 bit OS)

Download and install Configator - http://www.newvegasn...le.php?id=40442 - to the same above directory, it will put a shortcut on your desktop. Run this before running the game (it explains all the options in the program but don't launch from there.) (Run as many background loads as you can.)

Download and install FNVEdit - http://www.newvegasn...le.php?id=34703 - to the same above directory. Run it to see if there are any fatal conflicts that abort game loading.

Download and install the FNVEdit manual - http://www.newvegasn...le.php?id=38413 - to learn, at least, how to MasterUpdate and MasterRestore your mods. (Make sure you read the description pages and Readme's of all your mods first because some mods won't work right MasterUpdated, very few, but they should state this)

Download and install BOSS - http://www.newvegasn...le.php?id=35999 - to the same above directory (I use the installer version rather than the Archive because I find it simpler, it will install a shortcut to your desktop. Run this to sort your load order.)

Download and install Better game performance - http://www.newvegasn...le.php?id=40128 - run it dead last in your load order.

Don't use Stutter Remover until they update it for 1.4. Don't use d3d9.dll if you,ve updated you video card driver in the last year. (Some mods add this so check your 'fallout new vegas' directory.)

If you're bound to use existing shaders then make sure you have Shaders enabled in your .ini (Configator is the easiest way to do this.)

Avoid adding mods that have not been updated for 1.4, but if you must then add them one at a time starting with global mods (Project Nevada, FOOK, IWR etc.) because there have been many conflicts with these as a result of the 1.4 patch.

If anyone has caveats to the above, other suggestions or things that worked for them then please add them here. We have to get 1.4 working for as many people as possible before we have to start all over again when 1.5 gets released!