one different is that a 32bit operating system only can recognize up to 3GB of memory or 3. something GB, while a 64bit operating system can recognize more than 3GB. so right now you are only using 3GB of RAM instead of 4GB. also they are a lot of programs for 32bit operating system than for a 64bit. in fact you may find a problem when installing a 32bit application in a 64bit operating system, in some cases they dont install at all or just dont work properly and therefore you have to see if the provider have a 64bit version in order for that particular program to run properly.
Vista 32 to 64 bit keys are interchangeable. So as long as you know someone with a vista x64 disk then you can switch whenever you fee like it. Though I must say that I run the 64 bit version of vista and have not come across a program that would work in vista 32 and not in vista 64
Yeah, when Vista came out and it was made known what a memory hog it was, and RAM fell in price so low that buying 4gig was simply an automatic thing to do, Microsoft was overwhelmed with people who did not know about the 4 gig 32bit OS memory barrier.... wanting to know why all of their memory was not working. So they changed the display to simply show how much installed RAM (Random Access Memory) you have, not what it is able to use. What everyone fails to think about when they ask this question is that there is much more memory in your system than just the RAM that you physically install into your memory slots.
A 32 bit OS can use a max of 4 gig of memory. But this must include ALL of the memory in your system, such as memory on your video cards, CPU cache, HDD cache, controller memory, etc.
Windows will assign all of this internal memory on your hardware for use first, then whatever ever is left over that makes up to a total of 4gig is finally lastly addressed and available for your main memory, or RAM. Now the amount of memory Windows is showing that you have is not accounting for all this background memory it must address to be able to use, it is only showing how much RAM you have for usage(and remember with the update to Vista, it is now simply displaying how much memory you have installed, not how much it can actually use). This is usually on the average system with 1 -512meg video card, around 3~3.4gig of memory. If you add another 512 meg video card for instance to run Crossfire or SLI, then you would only have 2.3~2.8gig of main memory left for use.
See how that works?