HPX170 pros: cheaper, smaller, lighter. Has magnified focus assist, better/faster autofocus, CCD chips are immune from flash banding or skew.
AC160 pros: newer, better low light, sharper image, less grain, much longer zoom range, overcranking happens in 1080/60p instead of HPX170's 720/60p, has HDMI for cheap monitors.
Subjectives: HPX170 records to P2 -- better (IMO) than SDHC/SDXC, but more expensive too. AC160, on the other hand, can simultaneously record to two SDHC cards, pretty much ensuring 100% reliability, and SDHC is less expensive.
Problem with Vegas is that it can't/won't edit any files from P2. You have to (HAVE to) get Raylight from www.dvfilm.com in order for Vegas to work with the HPX170's files at all. Not really a big deal, just something else you have to factor in.
Both good cameras, HPX170 is great ergonomically and is a great size; AC160 has a lot longer lens and is, accordingly, quite a bit bigger. If you're doing a lot of handheld stuff, I might lean towards the HPX170 just because of the size difference, although the AC160 is quite well balanced and handles very well for such a large camera.
If you're going to heavily rely on autofocus, be aware that the smaller lens and lower-res chips of the HPX170 combine to create snappier, faster, more locked-on autofocus than the AC160 does with its bigger lens and sharper chips. There's a tradeoff there.
If you're primarily manual-focus, and you want the less-expensive/longer-recording SDHC cards, the AC160 has a number of significant advantages over the HPX170. But it's also more expensive and bigger.
Finally, if you like P2, and you like the AC160, consider the HPX250 -- that's a great camera, it's the same body as the AC160 but recording 10-bit 4:2:2 to P2 cards. More expensive still, but there's a great rebate running on it right now.