No, LR4 works with 32bit. But you'll need window Vista or higher. Will not work on XP regardless of 32 or 64bit.
I'm using Lightroom 4 on Windows 7, 32 bit, 4 GB ram. On my system it is performing acceptably. I have no complaints. There are, however, those who will tell you that you really want 64 bit. They will mention performance problems. There are those who have 64 bit computers who are experiencing performance problems as well. So it depends on the computer, and the only way you'll ever know is to give it a try. Take note that Lightroom 4 will NOT run under Windows XP.
I would discourage you to use Lightroom 4 on a 32 bit PC. You can expect out of memory errors when exporting raw files or rendering 1:1 previews. Develop module is slow and not stable (brush).
See also this thread of me: http://feedback.photoshop.com/photoshop_family/topics/lightroom_4_i_cant_export_web_galler y_missing_raw_files
I recently changed to 64 bit and the memory and stability problems have disappeared and Lightroom is faster too. My system is Windows 7 Home premium 64b, i7, 8GB memory and Nvidia GTS450 video card.
Message was edited by: janh1948
I had plenty of performance issues with Win 7, 32-bit, 4GB ram using LR4, including freezing and out of memory issues. I gave Adobe time and waited for LR 4.1, and my problems disappeared. I shot 700+ images a few days ago, and imported them with a preset and rendering 1:1 previews, with no problems. I would sync about 100 images at a time, and, again, had no problems. Exporting 50+ at a time, no problems. Like others have said, there are still problems out there. Maybe because of their system setup, maybe not. All I know is that it works for me.
I was about to order Lightroom 4 then discovered the reference to 64 bit. My PC is 32 bit. Does this mean Lightroom 4 won't work on my PC and I will need a new one?
you mabye don´t need a new PC for 64 bit.. just a new operating system.
but that depends on your PC hardware.
RAM is cheap these days and i would definitely go for a 64 bit operating system with more then 4GB ram when you want to have fun with lightroom.