Hard disc cameras were a valid option for a while, but I'd say their days are over. Flash memory has become cheaper and camcorders today come with plenty of it. A camcorder I'd recommend (not based on personal experience though, but un-biased tests and forum postings) is the new JVC HM400. Comes with 32 GB memory, enough for almost 3 hrs of highest quality setting AVCHD video. The more expensive Canon competitor comes with 64 GB. So I'd say buy another 32 GB memory card and you're set.
AVCHD is in it's third generation now and has matured. I'd say the first two generations where inferior to HDV of lets say a Canon HV20. The codec in the mentioned JVC cam is full 1920x1080 HD (unlike HDV in the first <1000$ 2007 HD camcorders). The AVCHD codec looks better now then comparable HDV footage. The JVC HM400 as far as I read is great for daylight shooting - good sharpness, no zealous gain, no over-saturated colors. In low light not so good. I read it has a unique consumer camcorder feature where you can deactivate the gain - I wonder if that improves concert shootings, where you always have the problem of the camcorder pumping light levels up and down.
Not sure if you really need Adobe CS4. On the Mac iMovie or Final Cut Studio bring the footage onto your computer, but I guess you're on Windows. AVCHD is still a pain in terms of CPU use, so you will need a decent computer. Some people say AVCHD is a pain because one wouldn't edit it directly but rather recode it into some intermediate codec first. True, but that's what I'm doing with HDV right now, too. In case you're on a Mac I got a little secret hint for you: Toast 10, little burning app, does the conversion from AVCHD to all QuickTime codecs ... 100+$ app.
.avi is just a container, so that doesn't say much.
Looking at the AVCHD codec I would rather ask myself if you need progressive framerates (24p) or if you can live with interlaced (60i). The mentioned JVC camcorder lacks progressive shooting, which might be a no go for you. Now 60i has it's benefits, converted well it might look better then progressive footage thanks to the better temporal resolution. So read up on the good ol' pull down.