If you haven't downloaded it already, do so. Windows 7 RC1 is free and comes with a key that expires in July 2010. I don't recall Microsoft ever being that generous with a release candidate. The download should be available into June of this year.
I downloaded and installed Windows 7 RC1 and installed the x86_64 version (clean install) on my Windows Vista computer. So far, the Windows 7 experience has been worlds better than all my early experiences with Vista.
The install was easy, almost too devoid of options. Apart from the disk partitioning, you really don't get any control over what gets installed. All of my hardware worked right out of the box (AMD Phenom 9550 Agena quad core, ASUS M3A-H/HDMI motherboard and XFX 9800 GT nVidia video).
I have dual monitors, a 22" wide screen 1680x1050 LCD and a 19" 1280x1024 LCD and both were detected properly, set to the correct resolution and, get this, "Extended Desktop" was enabled by default. Wow, this is the first time I've had an OS install and not use mirrored desktop as the default.
Following the install, I ran Windows Update and, in addition to the OS updates, I allowed it to install all of the driver updates. In the past I have never had good luck using driver updates from Windows Update. Either they flat out did not work, or they were so out dated that it was laughable.
In this case, WU actually had the latest bleeding edge nVidia driver that adds support for some of the new desktop features of Windows 7. Those installed and work great (even included nVidia control panel).
The bad news, the ethernet driver "Atheros L1 Gigabit Ethernet" installed and promptly failed to link up with my router. A few reboots later and I still couldn't get it working. I used the "Roll Back Driver" button in Device Manager, taking the driver back to 22.214.171.124, and the card began working immediately.
One application that I see getting a lot of use is the "Resource Monitor" that can be launched from the Task Manager window. It shows you process information from four different view points; CPU, Memory, Disk and Network. Granted, most, if not all, of this information can be viewed using other tools, but this tool puts it all in a single GUI. I don't know if Mark Russinovich had a hand in developing the tool, but it certainly looks like a Sysinternals type tool.
Under My Computer -> Network, I can browse my DirecTv HR20 HD DVR, unfortunately the connection gets refused. Maybe at some point DTV will open this up and allow us to watch recorded shows on our PCs without having to install their clunky software.
Oh, and Windows 7 RC1 passed the Left 4 Dead test with flying colors :-)