I've got some results to report:

My 2500k is linX stable (20 runs, all memory used) at 4.9ghz using a vcore of 1.385. I'm using the latest linx from the first post of the linX thread on this forum, but I'm not running windows 7 sp1 yet.
At 1.385 vcore, my setup is not prime stable.

I tried to recode some movies with Handbrake. Handbrake is the most cpu intensive program I run (other than benchmark tests) on my computers, with the usage monitor showing 100% utilization on all four cores while running.
At 4.9 ghz at my linX stable vcore of 1.385, I bluescreened with a stop 124 error, which in this scenario I interpret as insufficient vcore. So I bumped the vcore up two notches to 1.395, and I recoded two rather long movies without any issues (it took about 7 hours).

So for my purposes, I would have to assume linX (sans SP1) is not an accurate assessor of system stability. Now even at 1.395 vcore, I'm not prime stable, so perhaps prime stability is overkill for my needs. I plan on downloading SP1 this weekend and seeing what my new linX stable vcore turns out to be.

Just to be clear, to enable AVX instructions on these chips, one must install windows 7 SP1 (for which there is a link a few pages back in this thread) and install the latest linX (from the first post of the linX thread on this forum). Is this correct? Any other actions that must be taken?