How do Linux Threads Compare to NT Threads?

BurnMage asks: "I run a small network at a company that does heavy web and graphic work, as well as digital video production. The DV stuff is absolutely wonderful, cutting edge really nice hardware that costs thousands of dollars... and is only supported on the Windows platform. My personal experience with the machines has really been a constant nightmare until recently; we have gotten things running relatively smoothly. We use the DVRex and RexFX from Canopus, beautiful stuff and great tech support... but a few small messages asking why not port to Linux had a couple people muttering that threads in Linux 'aren't properly implemented'. I have also heard the same about NT. What's the story? I want a clear answer to post on their site."