I am only using SL clients on Windows 7 64 bit (and MacOS sometimes). With any client I hit a memory limit in the 32bit viewer quite fast, during live events with lots of people and thus lots of objects and textures. At that point almost all clients crashe cause it tries to allocate memory and fail.
That memory barrier seems to be something like 1,5 GB RAM, in Windows Task Manager shows as Memory (Private Working Set). Sure this is not the 32bit Limit, which is a bit more that the double of that. But still, this probably would be no issue with a 64bit client.
Whyever, Cool VL Viewer can eat up more memory than any other client without a crash, I got around 3,4 GB or something memory shown and the client did NOT crash by then. I only experiences some client slowing down, probably because of lots of searching and working around in memory lists/caches.
And yes, with a system like this it would be nice to move on to a 64bit version of the viewer: