I've just got my first 64-bit-capable laptop (previously I've only dealt with 64-bit on servers). Of course the first thing I am going to do is to format the hard drive and install Ubuntu instead of Vista, and the question is should I install 32-bit or 64-bit Ubuntu?
Here are the details which can matter:
CPU: Core 2 Duo 2 GHz, RAM: 3.45 GB. I am going to intensively use multitasking, virtualization (VirtualBox) and run memory-heavy Java, C# and native applications.
I ask because my experience shows that 32-bit desktop systems usually work faster and consume less memory. And as far as I know (have read somewhere, never tried myself) 64-bit Java is known to be extremely RAM-wasting compared to 32-bit JRE.
Best Answer
Points to consider:
Because address space is larger, applications do consume more RAM. It's ralatively tiny but can be a deciding factor if RAM is the deciding factor (eg in a rented server). Desktop and even laptop RAM is cheap though.
Native programmes do run faster but it's not always a tangible difference. For big things however (as you suggest you'll be doing) it can make a real difference.
Compatibility is larely irrelevant these days. Flash is available and Sun Java works (there's even a native JRE that's fairly complete). You can run most pure 32bit binaries just fine, it's just a case of installing its dependencies.
Security is not really a factor. 32bit kernels support NX bits and most of the touted features.
Neither is the total memory limit unless you have processes that require more than 4GB of RAM. The PAE kernel works.
You shoud also look to the future. I don't like to reinstall when I can help it. The future is 64 bit and its performance gains will only increase s GCC gets further extended register optimisations.
In balance, unless this was a very RAM-tight system with no scope for upgrade, I'd go 64 bit.