Just having a look through past threads and spotted this one, thought I'd chime in about the Archos AV500 stuff.
I've owned an AV500 for years, along with the camera attachment.
Here's a couple of videos I took years ago with the AV500+camera attached to the forks of my Urban Mover:
Archos Bullet Cam Day - YouTube
Archos Bullet Cam Night - YouTube
The digital mini-cam is actually a Sony HAD 420 line CCD 1/4" sensor, the Archos records video at 640x480 max resolution, at 25fps (PAL) or 29.97fps (NTSC). The lens on the camera can be replaced so you can have a wide angle picture (1.8mm = 180 degrees, 2.5mm = 120 degrees, 3.6mm is the standard that comes with most cameras).
The AV500 is a very nice device, if a little old now, one major downside is that the harddrive is locked in, it is possible to physically replace it with the right tools but the firmware refuses to use another drive, so don't buy one with a borked drive in the hopes of simply putting a new drive in and make sure you never drop it.
One aspect almost everyone overlooks when buying a mini DVR with internal/external camera setup is the type of camera pickup being used, if it's CCD then you're looking at a global shutter (good) but CMOS and you're more likely looking at a rolling shutter (bad). Don't know the difference? Have a look at this:
CCD/CMOS-
And when you're recording from a vehicle with a rolling shutter CMOS camera you may end up with footage looking like it was shot through a jelly:
CMOS Vs CCD Rolling Shutter Effect + Jello Effect Kawasaki ZX-11 - YouTube