drapacioli :
You can't change from 64-bit to 32-bit OS without doing a full reinstall of the system. It would be easier to just upgrade the RAM, it's a fairly cheap and easy process. What PC do you have?
Agreed.
Also, it appears that Windows 8 might require LESS MEMORY than Windows 7, not more:
http://googlechromesupportnow.com/comparing-memory-usage-in-windows-8-vs-windows-7/
"...Therefore, it is clear that when comparing Windows 7 vs Windows 8 memory and system resource consumption, all such added features help the modern platform run low on assets but faster than previous editions. "