On 64-bit Windows systems running I/O intensive application, I have sometimes faced the issue that, since the kernel is having plenty of address space at hand (compared to the 1GB on 32-bit), it may decide to use that memory for its caching mechanism but sometimes in a too ambitious way.
Microsoft very recently release an add-on called “Microsoft Windows Dynamic Cache Service” which allows administrators to gain better control over the system’s cache behavior and therefore reducing one type of intensive I/O’s provoked by the cache manager: read I/O’s.
Extra information from the Microsoft Advanced Windows Debugging and Troubleshooting Team’s Blog:
Note: the download includes the source code as well as a version compiled with the debug flag set, (unusually!) cool!