Memory interface on the gpu affects its memory bandwidth and is not something you need to worry about. it has nothing to do with the CPU or OS being 32 or 64 bit. whether the gpu is compatible with the rest of your system is another issue.
If you intend to use that card for gaming there are much better choices, that card is extremely low end, on par with the HD3000 graphics in sandy bridge
The two relate to different hardware, they will not be incompatible with each other.
For instance, my Graphics card is 256bit, while my OS is 64bit.
Also both arent even really the same thing, on GPU's the bits refers to the amount of bandwidth, while for an OS the bit refers to how much physical RAM it can use.