[flopdos]

But it plays fine on my LCD (I'm new to this whole connect-your-computer-to-TV thing).

It's most noticeable with the live-action videos.
Other than that, cartoons and gaming videos seem smooth.

It applies to all videos - from AVI to MKV and h.264

Here are some specs:
C2D E6750 @ 2.66GHz
BFG 9800 GX2
10' HDMI Cable
22" Acer LCD Monitor
32" Sony Bravia HDTV (model number slips my mind, I can provide later if needed)

Any idea to what the problem is, and how I could fix it?