Any modern day system will be able to run a 64 bit OS (may be not an atom based system).. All you would need is a CPU supporting 64 bit and drivers for your video card/chipset.. Am very sure you can run a 64 bit OS.. You can list your full system specs to gain full confirmation..
What processor are you using?
Anything above Athlon 64 is 64Bit compatible, "Athlon 64X2, Athlon 64FX, Athlon 64" since these are the compatible processors of your Mobo, I guess, It is 64Bit compatible.
If you want more details for your processor, then try using CPU-Z
from here http://www.cpuid.com/softwares/cpu-z.html
and give me the Processor Name, I'll tell you whether or not it's 64Bit compatible.