On these questions:
People are recommending 64 bit, can you explain why? Is it just so you can have more then 3Gb of addressable RAM that 32 bit gives you?
And how does Visual Studio benefit from all this extra RAM?
I went from 64 bit XP back to 32 bit due to 90% of the software I was using only being 32 bit anyway and I had issues with drivers and some software with 64 bit.
A number of reasons.
Vista, as far as I know, has much better 64 bit support than XP. It is more well advertised than 64 bit XP, and more popular. Driver and software support should be much better for 64-bit Vista.
The 64-bit switch is in progress right now in the computing industry. You might as well switch. Microsoft made the serious leap to 64-bit already, and many have already followed suit. Those who haven't switched, will soon, most likely.
As for the technical benefits, there aren't many aside from the higher memory limits. Vista will certainly allow you to take advantage of the 4GB+ of RAM if you have it on 64-bit though.
XP 64bit wasn't ready for prime time, there were no drivers for it. In Windows Vista 64-bit this isn't the case. So if you are looking to install Windows Vista go 64-bit if you are keeping XP stay at 32-bit.
Bigger is always best? The RAM thing is the major advantage, and the increased address space. I guess as long as drivers aren't an issue, then why NOT 64bit?
People are recommending 64 bit, can you explain why? Is it just so you can have more then 3Gb of addressable RAM that 32 bit gives you?
This addressable RAM limit is not a problem for a regular user, but it is pretty critical on DB configuration, scientific computing, etc...
And how does Visual Studio benefit from all this extra RAM?
Does it??? If you want to compile faster you can gain up to 20% compilation time compiling directly from a ramdisk partition. I went from 64 bit XP back to 32 bit due to 90% of the software I was using only being 32 bit anyway and I had issues with drivers and some software with 64 bit.
Switching 64 bits for a regular dev station is probably useless.
Vista x64 has been a very pleasant experience for me. There are a couple of edge cases, but most software and drivers work fine with it at this point. The biggest practical reason I see to use it is that you can load up on RAM (say 6GB or more) and then dedicate lots of it to virtual machines and other apps that require lots of memory (like Photoshop). If you are only using Visual Studio and maybe a couple other apps day to day, then it might not be as beneficial, but I find myself 0ften running 10 to 20 apps at a time (seriously) and the extra RAM is critical.
64-bit won't be mainstream before most programs are availiable in 64 bit versions. And who make programs? Developers, developers, developers!
See my point? If developers don't make the shift, how is 64-bit programs going to be mainstream?
Other than that, there is of cource more reasons:
DotNet rocks had a recent show all about the benefits and pitfalls of going 64-bit from a .Net developer perspective.
http://www.dotnetrocks.com/default.aspx?showNum=341
There are the obvious benefits of having access to more RAM in windows, as well as the obvious possible downside presented by unavailable drivers (which not only have to be 64-bit, but signed and certified as well).
Other points made are in that if you ever need to test anything you are developing under 64-bit, the only way you can do that is on a 64-bit OS. You can always create VM image to test under 32-bit from a 64-bit OS.
There are some gotchas in terms of p/invoke calls not always working across 32/64, as well as Managed DirectX not working well under 64-bit, but on the whole I think its something people are going to be doing more as time goes by.
Another technical benefit, aside from the increased address space, is that 64bit apps always use DEP, so you are forced to fix those bugs and potential security holes.
I switched from 32 bit Vista to 64 bit and haven't looked back. I have only had a problem with one device (a multi-track firewire mixing board) - but everything else that has worked for 32-bit works for 64. Throw in the ability to add piles of cheap RAM, and I don't see any reason why anyone would stick with 32 if the processor supports it.
If you're really unsure, use Vista's much improved multi-boot functionality and install 32 bit XP and 64 bit Vista on the same machine on different partitions. I did, but to tell you the truth, I haven't gone back into XP for at least 9 months now.
"There are some gotchas in terms of p/invoke calls not always working across 32/64, as well as Managed DirectX not working well under 64-bit, but on the whole I think its something people are going to be doing more as time goes by."
This is caused, in .net, by having the AnyCPU flag set. AnyCPU on an x64 machine will run the process as a x64 process, which proceeds to explode when attempting to call/load a 32 bit dll. Since those libraries are 32 bit you need to set the build to x86, to ensure the app will run as an x86 process, if on an x64 machine it will run in WoW.
Signed Drivers. No more "Unknown Device Driver" blue screens, drivers that cause issues are found out, and rightly blamed for their crashes.
Signed drivers also means the drivers are current. Manufacturers that used to get away with updating a driver once every 2-3 years had to get signed/certified. Which means the driver is relatively current and had to pass basic "is this total crap" test at Microsoft.
This "lack of driver support" I've always seen as a boon. Forcing manufacturer certification.
More address space. Others have mentioned that this allows more RAM, which is true. But it has more impact on memory management performance. It also means having 4 gigs RAM and a graphics card with 512MB on it will be fully used by the system. On a 32 bit OS the system has to decide, out of the limited addresses, what hardware gets what range, physical RAM loses.
Then there is always the possibility of using more than 4 gigs RAM, good for when you have lots of VMs
x64 Vista loads core OS processes/services, during boot, into random addresses. Giving some exploits a 1/256 chance of picking the right memory location, instead of 100% on a 32 machine.
No kernel patching. None. Nada. Zilch. It does mean some Sysinternal tools do not work, however it means xyz spyware/virus cant maliciously apply the same techniques as sysinternals to hide forever, intercept calls, etc. (this is what keeps out some anti-virus software... as well as viruses)
Another advantage of 64 bit:
All the registers associated with the microprocessors are 64-bit. This enables High- precision computations and 64-bit arithmetic to be performed in fewer clock-cycles as compared to 32-bit microprocessors. In certain cases like 64-bit multiplication, it is twice as fast.