What are the benefits to running a 64 bit version of Ubuntu?

A 64-bit OS has support common to the CPU and the OS for 64-bit types.

A 32-bit OS also has support for 64-bit types, but because it doesn't know anything about the CPUs support for 64-bit types, it's likely to treat them as a union of 2x 32-bit variables. A program that uses 64-bit types on a 32-bit OS will be far worse off.

The theoretical maximum value of a single 32-bit variable is 2^32 or 4,294,967,296. 4GB has the same number of bytes. That's why people believe 4GB to be the maximum amount of addressable memory for 32-bit OSes. Subtract the kernel memory, video card and whatever else they want to dribble about and you end up with 3GB. However, the OS may choose to use another 4 bits (which is known as Physical Address Extension) and as a result address 64GB of RAM instead. Both 32-bit Windows Server OSes and 32-bit Ubuntu support PAE.

So we've covered the myths about 32-bit OSes. What about 64-bit OSes? Well, we need to take a look back at what 64-bit really means. When a processor is 64-bit branded, it has at least one 64-bit register and supposedly uses a 64-bit bus (though this is up to the mainboard). Suppose your CPU that has only one 64-bit register, that means your programs can (between them) store one 64-bit value before they have to resort to using the old 2x 32-bit type union trick. Is there really a significant performance boost there? How do you know how many 64-bit registers your CPU has? Well, unless you're an assembly programmer you won't know where to look, so it's better you focus on L2 cache capacity if you're in the market for processors.

Having ranted on about that, AMD Turions are indeed 64-bit processors (though I don't know how many 64-bit registers your unknown model has). The benefit is that your OS would be aware that your CPU has some support for the 64-bit type registers. The performance increase could range from miniscule to significant depending on how many registers your processor has (as well as other performance factors such as L2 cache capacity, FSB frequency), and how much use they get. There could be issues, however. When I installed Ubuntu AMD64 on my computer, I had to compile the drivers for my wireless. The 32-bit drivers were available in binary form. I'd recommend running it from the CD/DVD (livefs) just to make sure everything works before you install it, if you decide to go through with it.

1st thing is the ram that the OS can take.

Another is that the 64 64 bit system has over a 32 bit one is the ability to handle math computations better. For educational institutions, corporations or anyone doing large amounts of calculations/processing this translates into a decent block of time in savings. The average PC user on the other hand will only see a slight upgrade in performance.

faster however it only makes native 64bit apps faster.

You would be able to use all four gigs of your ram because 32-bit operating systems only support 3 gigs of ram

"Who would benefit running a 64-bit OS?" Mostly businesses, universities, scientific groups, and government. As a home user, if you produce videos, computer art, or develop programs, 64-bit systems would be an advantage.

Regular, everyday office productivity and web surfing will show no advantages at all, but graphics processing and scientific calculations will go much faster.

It just depends what your uses are. Even gaining the extra 1GB of system RAM may not actually give you a speed boost- unless you were routinely using up all of your 3GB, which is doubtful...Probably the biggest boost in that PC is moving from MS bloatware to Ubuntu. I am running Linux Mint on my desktop & it is blazingly fast compared to my son's new PC running 7...

I would probably stick with 32 bit Ubuntu. I've just ran into too many issues with 64 bit Ubuntu. What I do is have a partition for 32 bit Ubuntu, and another for 64 bit Ubuntu. I'll then edit video and that kind of stuff in the 64, and in the 32 I'll do daily work.