okorop
LinX is OK at memory testing. Not sure if it can be compared with MemTest, but it definitely does detect serious memory errors. And according to ReverendMaynard it even outperforms Memtest86.

Falkentyne
Well, MemTest is a nice tool, but the chance of corrupting the OS completely due to memory overclock is not that high. And, honestly, I don't think it had such a great impact on OCing's popularity.

jcool
i7 seem to be very different from previous CPU generations. No wonder that stress-testing apps act weird on them. I'm sure i7's specifics will be taken into account in newer stress-testing software.