My 9150 (DXP051) shipped with Windows XP.  I later installed Windows Vista 32 bit.  I now wish to use Windows 7 but need advice on which version to use, 32 bit or 64 bit.  I have tested installations of both 32 and 64 bit versions without experiencing any immediate problems but is there any reason to avoid one version over the other on my machine?  My peripherals and various software installations have not presented problems under a 64 bit operating system.

My processor, an Intel Pentium D(940) CPU 3.20GHz dual core is 64 bit but as my motherboard accepts a maximum of 4Mb memory I think I may be limited to 32 bit elsewhere such as the chipset?  I appreciate that I cannot take advantage of the greater memory capacity of a fully compliant 64 bit motherboard (Windows reports 3.5Mb available) but if my machine is operating well is there still a performance gain using 64 bit at processor level?  Will the system be more stable with a 32 bit Windows installation?

Your thoughts will be appreciated.