Handbrake is fanstatic. It has an iPhone preset that yeilds pretty good size (about 350Mb per hour of video) which looks great on my OG iPhone and also on my 36" 720p TV. Not sure how it'll scale to 1080p. Handbrake is really easy to use but offers a ton of extra features if you need them. I just stick with the preset, though. It runs great on Intel Macs and Windows, but if you have a PowerPC-based Mac, it runs on the slow side.
One caveat is that it works best with MPEG sources, but you may be able to use other sources as well. Not sure about Windows Media formats. It also (no longer) works with DRM, so you need another program (like Ripit) if you are consuming DVDs.