Dheeraj Gautam asked this question on the Sony Vegas user group on Linked-In. I thought the answer might be useful to others so I am posting it here too.
32 more bits? Sorry couldn't resist :-)
Vegas pro 64 bit is a fully 64 bit application. What this means is that on a 64 bit operating system like Windows 7 64bit Vegas can use far more RAM.
On a 32 bit system the maximum amount of RAM available is 4Gb. With HD footage and larger and larger files to deal with this is often not enough and so the computer has to keep swapping data from memory to the hard disk. Causing slow performance and sometimes crashes.
On a 64 bit system you can address up to 192Gb which provides far more room for data to be kept in RAM. (Theoretically up to 16Tb but Windows limits this to 192Gb :-)
The down side is that your plug-ins also need to be written for 64 bit in order to use them in 64bit Vegas. There are new 64bit plug-ins coming out every day and the OFX architecture that Sony have adopted means we will get access to many more plug-ins.
I personally run Vegas on a 64bit system (with 8Gb of RAM), but I have both the 32 and 64 bit versions installed. I can work on a project in the 64bit version with all the performance benefits that brings and then if I need to use a 32bit plug-in I can open the same project in the 32bit version of Vegas. Best of both worlds and one of the reasons I love Vegas.
Any comments or questions gratefully received. Neil