For the following: you should not go ahead and make Fallout: New Vegas Large Address Aware yourself as it is possible, but not likely, that that would interfere with a future patch.
An overview of Large Address Aware and a tool to manage that settings with the programs you have on your system is: http://www.techpowerup.com/forums/showthread.php?t=112556.
Basically, the short points:
Normally a 32-bit program can use up to 2GB of memory. Fallout: New Vegas falls into this category.
If a program is made Large Address Aware, and the memory is available, then under a 64-bit system the program can use up to 4GB of memory with no additional changes at all. On a 32-bit system the program will still have a 2GB limit, but, if the user makes a further operating-system change then the program can use up to 3GB of memory in some circumstances.
Giving a 32-bit program the ability to use more than 2GB memory is a "bridge" setting between 32 and 64-bit systems today. It gives the major benefit, partially, of more memory to a program that only 64-bit native executables enjoy.
Depending on the number and type of additional modifications that can be added to Fallout: New Vegas having more than 2GB of memory accessible to the program may, may, reduce crashes.
Changing this setting for future executables would be a trivial task on the developers end.
What does anyone think?