Instead of SysInternals DiskMon, which gives low-level disk access information, try
FileMon, which tells you which files are being accessed by what. I've found this more useful for determining which programs are accesing the disk(s), e.g. it showed me how heavy the Windows Search service and Symantec Anti-Virus are. (Spurious disk access is a bigger issue on my SSD-equipped eeePC 1000 "netbook" than on a standard desktop PC.)