[trevorbramble]

I have 4GB system and 512GB video memory installed. However, I only upgraded from 2GB after installation because the already-heavy Java apps I use (Eclipse, SQL developer) now required twice the memory.

As the other commenter mentioned, there are the CPU optimizations to consider, but what decided my final transition (I've tried it out a few times over the past few years) was when System76 moved to shipping their systems with the 64-bit distro installed. I want to maximize their ability to support me, so when I did a fresh install on a new drive I opted for 64-bit as well.

Most of the problems of compatibility with 32-bit binaries have been trivialized or are routed around easily enough these days. Though 64-bit Linux was never as much hassle as x64 Windows. ;^)

[gchpaco]

Java is not a good benchmark. Sun's JVM won't even pack memory (if you have a class with 64 "boolean" variables, it takes header + 64*4 bytes, not header + 64/8 bytes, for some reason that is utterly unclear) unless you use arrays of primitives, and my experiments indicate that it just shifts to packing on a 32 byte boundary to packing on a 64 byte boundary on a 64-bit VM. That is to say the Sun JVM does implement the naive "everything is twice as big" translation even though it needn't.

Of course the 32-bit JVM also has a 2.5 gig or so address space limit that makes no goddamn sense whatsoever, so if you want to process more than 2 gigs of data for any reason you have to either do it offline or you have to buy twice as much memory and do it on a 64 bit VM.