Just upgraded my mobo with an Opteron AMD64. My old Slack 11 system booted perfectly, with no changes.

If I switch to a 64bit version, will I get any performance increase. Or will it just let me address more main memory.

Is it worth the effort to rebuild my OS.

Cheers.

If you have an x86_64 system and are only using 32-bit or only using 64-bit, technically you have a broken OS. They'll work, but won't be standards compliant. The x86_64 architecture is multilib and any standard-compliant OS must support both the 32- and the 64-bit ABI. I only mention that because if you choose 64-bit, you'll have to play games with Firefox et. al. to get 32-bit plugins to work. If you choose to comply with the standards, you can just use a 32-bit Firefox until 64-bit plugins hit the street.

Whether or not you see a performance increase depends on what you are doing. Reading/writing e-mail, writing a book with LaTeX, surfing the net, and other general purpose PC tasks will receive a performance boost, but you won't notice. Computationally intensive tasks like video encoding, mathematical or scientific simulations will receive a performance boost and you will notice. But you'll notice tasks that to 15-minutes on a 32-bit platform taking 7 or 8-minutes on a 64-bit platform. I run simulations and reduced the time of one simulation from ~40-hours to ~28-hours when I switched from 32- to 64-bit.

Depending on your choice of distro, and your needs.

I use mainly 64bit distros. My everyday distro is Debian Sid AMD64, and I have very few problems. Firefox plugins are the only missing thing, but I dont really miss them. Gnash is a good replacement for Flash, but it is easy to install Adobe Flash.

Other distros are also good, like Fedora, Ubuntu, SuSe, etc.

You won't notice much difference between 32bit and 64bit for general purpose tasks, however you paid for 64bit so why only use 32 of them

--Ian