First of all dont turn off indexing, you wont be able to search your computer quickly and its going to be a pain, especially because the new start menu was designed to be used with search.
Second, vista doesnt encrypt anything you dont tell it to. Its not encrpyting everything as stated before, this is due to a misunderstanding of Vista's contentent protection system that was added for support with Blu-Ray and HD-DVD, it doesnt run or take up any space unless your using those two formats that have the content protection enabled.
Second, let Vista do its job. It does ALOT more in terms of memory management then XP, especially on a new install. The best thing you can let it do when you get it is just let it sit for a while while it works itself out.
Vista looks at how you use your computer, it detects what programs you use the most and when. Based on that information, it tires to preload that data into ram before you use it, to make launching applications faster. You may see your hard drive be used more as a result, but all of this is put on a low hd priority, meaning requests from applications your using get loaded first. Actually, the more RAM you have, the more its going to use your harddrive, as Vista tries to fill up all your empty ram space, of course when you need that space the data gets thrown out.
You can actually watch this happen, if you press Ctrl + Shift + Esc you will pull up the task manager, on the performance tab one of the stats talks about physical memory. It displays three numbers, Physical, Chached, Free. When you first log on, or after closing a big program, you can see the free ram decrease as the chached memory increases, and at the same time your hard drive will be active, as its loading the data.
So go back and turn indexing on, and let vista do its thing. Also, you will see some active HD usage around 2-3 am on Wednesday, this is when Vista's disk defragmenter runs automatically in the background, I also suggest you let it run. And again, all this runs on a low hard drive priority, so it shouldnt effect you that much.