Honestly, the Crucial M4 and the Samsung 830 both have very good track records. The Crucial is slower than the Samsung. If you can get the Samsung for less, go with that one. I bought the M4 because it was cheaper and I knew that SATA II in my mid 2009 would be the limiting factor when it came to speed.
Another thing to consider is ease of firmware updates(admittedly, both drives have been out long enough that the current firmware version are pretty trouble free). The M4 can be updated from a bootable CD, while the 830 has to be updated from a windows installation on the drive.
So Samsung vs Crucial speed doesn't really matter in my case because I have SATA II. What about the above complaint about Crucial?
Also, where do I get the firmware CD? (Crucial)