The 0xF4 error, from what I am reading, is a rare one. Several processes and threads are necessary for the operation of the system. When they are terminated for any reason, the system can no longer function.
It usually points to bad memory including video memory. It is a hardware issue but finding out exactly which hardware is the task at hand. That being said, since the issues occured after the new harddrives I would highly suspect that, yes, it could be one or both harddrives. It could be also how you implemented the set-up through your cables or a bad cable itself.
Attach your minidumps. Run MemTest. If you can get it to boot up try your harddrive manufacturer's diagnostic tool.