You shouldn't install them all, first of all. When you download and run the installer, you get the choice to install everything, or pick and choose. Make the latter selection. If you have a previous version of something, they won't give you the choice not to upgrade, so if there's something you don't want to install, quit the installer and uninstall it first.Which programs in particular to install will be an individual choice. I already had Mail, Writer, Photo Gallery, and Windows Live Mesh installed from the beta. I had installed Microsoft Office since last updating the software, and so the installer offered me the "Outlook Connecter Pack". I'm not sure what it is, but it probably won't hurt.
Speaking of hurt, though, unless you really, really want it, don't install the Bing Bar. It's just a bad idea. It will try to take over all of your browsers, and seriously, who needs a toolbar in their browser?
I've never tried the updated Messenger, Messenger Companion, or Family Safety. I hardly ever use my hotmail account to chat, and I use Pidgin when I do, so I don't really have a use for the Messenger enhancements.
Writer is apparently a very good blogging tool that works with a lot of popular blogging sites (like Blogger, which hosts this blog), but so far, I've stuck with the web interface for composition.
By far the most useful tool is Windows Live Mesh. If you're like me, you have a bunch of pictures, music, files, and other documents on various computers. The file sets are simply too large to fit into a free Dropbox account, and you don't really need access to them over the web, at least not most of them, you just want them on your various computers. It's a hassle to keep all of photos or music organized in more than one place, so you don't. You keep them organized in one place, and (hopefully) make periodic backups to another computer just in case. Well, Live Mesh allows you to keep it organized the way you want it, everywhere you want it, and it doesn't matter how big the files are, because Microsoft isn't going to store any of them (except for a special 5GB folder, which it will store in the cloud and allow you to access from anywhere on the web.)
Microsoft doesn't upload your files to its servers, but it does keep track of them for you. Any change you make to your shared folders gets copied to the other computers where that folder is synced, and the copying is peer-to-peer, so if you're at home, it happens at the speed of your home network. It will also keep your files in sync even if you're not at home, directly from your other computer, not through their servers.
The management interface is pretty simple, though it's easy to miss the "Remote" settings, which allow you to connect to your computer over the Internet if you have enabled it on that device. Connect is a lot like Remote Desktop, if you're familiar with that. Basically, it's just like you're sitting at the other computer. You have to be running MSIE on the computer you're connecting from.
The web interface is a lot like the desktop interface, except in addition to your shared folders, you also have access to all of your devices as well, and you can see which devices sync to each of your folders.
Anyway, be warned: Windows Live Mesh is a resource hog on machines that need to turn on and off all the time.