i just would like to now what is the dirrfence between this 2?
my OP is windows Xp 32bit service pack 3.
i mostly use my pc for games and movies.
will you see any diffrence with the naked eye between this 2?
ATI 4870 hd 512mb
23" samsung LED 1920x1080
....naked eye difference between XP 32 bit and 64 bit....wow. In short...NO. And another thing, you are not using ALL the 4GB of RAM. For them to be completely used you need 64 OS. A 32 bit OS will not 'see' more than 3.2 GB or so (and that includes your GPU as well).
32 bit limits you to address 4GB of RAM. Your video adapter also uses the memory address space to address video memory, so you usually loose some of that 4GB. AS stated above it is usually 3-3.5GB that you can actually use in the OS.
64bit can address 16 exabytes of RAM and is usually capped by the OS. 64bit code is also larger and takes more memory but is usually more efficient when executing on a 64bit processor.
So if you have a 64bit system, 64bit OS, and 64bit app... It will probably perform better than a 32bit system, 32 bit os, and 32 bit app. But in reality most games and apps are still 32bit so you don't see much of an advantage. However, some games are coming in both 32 and 64 bit versions, in which case you will see a performance gain.
Rule of thumb right now, if you are on 32bit, just stay there. If you are upgrading, go 64 bit.
Some programs or applications are not compatible with 64bit, i've been told my friend that he can't install some games on 64bit OS.
I use win7 32 bit and never had a problem...
So, whether the advantage of 64bit is only "memory limit" or there's something else?
You can use more than 3.4GB of RAM on 32-bit, you can download OS mods that allow it... PAE (Physical Address Extension) allows you to do it. The 3.4GB limit is an arbitrary one enforced by Microsoft's OSs (not sure if Mac's do the same..), partially so they can sell more expensive OS's and partially because a 32-bit doesn't handle all that extra memory addressing as well. A 64-bit OS however, can address more RAM, but it will also do so more efficiently (as it is intended to be able to ).
So when using 64-bit apps and games, you will notice slightly increased performance and responsiveness. You wont necessarily SEE a difference.. that's the GPU's territory , but your OS will work more quickly.
Don't want to go into the theory of why, but yeah, 64-bit is faster than 32-bit, and can use the RAM beyond 3.4GB more efficiently.