I have mixed emotions on using a dSLR for video right now. Canon's, while some of them shoot fantastic video, none of them have continuous autofocus available during video, which means you're sitting there fiddling with manual focus the entire time you're recording. I believe right now only the Nikon D7000 is the only dSLR with full time autofocus during video aside from a few Sony's.
That said, I own the D7000 and while it's OK for video, I vastly prefer even my 10 year old Sony miniDV camcorder for shooting almost all types of video. For most people shooting family events, Disney, kids little league games, etc most dSLR's, IMO just aren't there yet. If you're looking at using it for capturing a boardroom conference or producing stationary, tripod mounted videos, it's not such a terrible thing.
Even on the D7000 the autofocus just really isn't that great for video and every time it does change focus, even with an AF-S lens, it's picked up from the onboard mic. Sure this can be rectified with an external mic, but now you're talking about more equipment to spend money on. Another point to consider with autofocus, most dSLR's that do video (even without full time AF like the Canon's) are using contrast-detect autofocus in video mode, which is FAR FAR less accurate and not nearly as quick compared to phase-detect AF. The exception here is some of Sony's dSLR's, that don't use the mirror in a traditional way, instead they use a transparent mirror that allows the camera to still use phase-detect AF all of the time.
There is also actual usability of a dSLR for video. You HAVE to use the LCD for shooting video*, there is no shooting with the viewfinder. If you're out in the sun, this can prove to be nearly impossible. If you're trying to hold the camera up over the crowd during a parade, you now can't see what you're shooting (* with the exception that some dSLR's do have a tilt / swivel LCD), let alone try to hold the camera up, see the display and focus with your other hand. There are other issues, like hot pixels as the sensor heats up as well as the length of shooting. I believe Nikon has one of the longest recording times at 20 minutes @ 1080p. The Canon 7D is limited to 4GB, which in 1080p comes out to just over 11 minutes if memory serves me. You're also limited by other technical issues that large sensors and other factors bring into play like rolling shutter (the "jello" effect), aliasing, etc.
Long story short, dSLR's for video, IMO just aren't ready for primetime when it comes to "off the cuff" normal family style shooting. I feel you're much better off going with a inexpensive, quality HD camcorder. The only ones out there that I could even expect to have some decent usability would be a few of the Sony's that use a transparent mirror. Those have better AF in video than anything out there. In addition, they have a tilt LCD AND an EVF, so you don't have to rely on a static LCD to shoot video from. The new A77 is really quite the beast of a camera, fantastic specs on that one! I'm not a fan of Sony (mainly because of, IMO, poor glass choices), but that new body sure is nice! If it wasn't for the limited glass selection and me being already so invested in the Nikon system, I certainly would have considered it over my D7K!
My 2c, HTH!