Your computer will not allocate physical memory above 4GB it to drivers or to programs that are running. This means that any driver using that physical memory (e.g. as a RAM disk) is effectively only storing data there - it's not being properly used by the system.
The only way this driver can be working is by circumventing the Windows physical page allocator - which makes your entire system unstable.
And anyway, these solutions always seem to miss the key point: The entire purpose of a 64-bit OS is to solve the 4GB limit on virtual and physical memory.
Using unsupported and potentially unstable/slow drivers to get the performance that a 64-bit OS will just give you for free seems perverse and stubborn. What possible downside is there for upgrading your OS to a 64-bit? It's not like your 8GB system won't have 64-bit drivers, since it must have come with them when you bought it!