Hi 
Are Cpu cycles to do with multi-core/multi-cpu? If so it's presumably possible for 32bit apps to take advantage. I think it's just a fluke that most of us think that 64bit machines tend to have more than 1 cpu/core and 32bit ones don't. Both technologies became well known around the same time.
Apparently the 4Gb Ram limit is a limit of the OS, not the apps. If the OS can read/write to more ram then i don't think the apps would be restricted. Apparently OSes that are 32bit could read more Ram with a different kernel module. With Gnu&Linux it's possible to swap-in the different module and i kept being told that "it's really easy". Something like the pae-something module.
Ram is used more efficiently by OpenSource programs, especially when using quite a few at the same time. My whole system is OpenSource apart from a few fonts and a couple of codecs and i seldom need even 1Gb. Movies and even fairly hefty games seem quite happy. I figure that if bits of my ram detiorate over time then i could always swap the sticks around to use the ones that aren't getting used at the moment.
If it feels like LO/OO are bumping into ram issues then it's more likely to be the limits you set (or the default ones) in
Tools - Options - Memory
If you imagine wires or cables as lanes on a motorway then double the number of lanes can carry double the number of cars. It's just that you don't always need to have that many cars on a section of motorway.
Regards from
Tom 