1. CD is correct.. x64 has 16TB ability but
2. You cant use 16TB unless the app is truly 64bit and it is correctly marked for that kind of memory use. Most apps in XP or Vista x64 will max at either 4 or 8GB. The motherboard must also support access to that amount of memory. Some professional server systems are designed like that and memory amounts in that range are reserved for special hardware and applications such as scientific research and CGI systems
3. Windows XP and Vista x32 will BOTH use up to 4GB of memory but they BOTH require the OS be marked to allow the ADDRESS SPACE above 2GB use
see this post:
http://www.simviation.com/cgi-bin/yabb2 ... 959973/0#34. A x64 OS does not require marking
5. A 32bit APPLICATION has ACCESS to up to 4GB if the OS is marked but the APPLICATION will NOT use more than 2GB unless its EXE file is marked to use GREATER than 2GB as FSX SP2 is
6. To use FS9 or FSX RTM or SP1 which ARE NOT marked for greater than 2GB use one must use special software to access the EXE file and set the >2GB MARKER in the EXE then save it. The same process can be done for any EXE file as long as the application is 32it. 16bit applications will not allow that change. From that point on the application will use greater than 2GB in x32 if the OS is marked as outlined in item 3
7. A 64bit OS can not run any 16bit application. It can run any 32bit application using a system known as WOW64 which emulates 32bit in a 64bit environment
8. The primary difference between the two is you will get a TRUE memory access to higher memory amounts in x64 where in x32 that is HARD LIMITED to 4GB. Video cards that have a 768-1GB+ memory on them will run better in a 64bit OS because that memory must be mapped to the address space. The higher the video card memory the less available to the 32bit OS where in x64 there is no limit.
9. 64bit applications are blazing fast compared to x32. Unfortunately there are still not enough of them out there and I am sure that will change as the years progress however in my opinion a 64bit OS runs smoother and faster than a 32bit OS and does not present you with memory limits.
10. You must research all your hardware and make sure the manufactures have 64bit drivers for that hardware before changing OS's.. or replace the devices that do not have 64bit support. In this day and age, most do.