[Skunkworks] Bytes for the week : 32bit or 64bit computing?

Been looking at various advantages and disadvantages of 64bit over 32bit. For example, on Windows machines, one key area that helps is RAM that can be pushed to 128GB removing the 4GB barrier that exists on 32bit. 64bit applications availability maybe an issue but anyone who has used say eg a MAC can relate to this better. Anyone using 64bit on this list. How has the performance been on running 32bit applications like broswers, office tools, games? Rgds.