I got a new PC a couple weeks ago, after using Windows XP 64-bit for three years. First, a quick word on XP 64 - never, ever, ever use it.
I had countless programs that wouldn't install, even things as basic and fundamental as iTunes and Amazon's game downloader. I had reboot issues that were not traceable to any piece of hardware, but have been replicated by a friend also running XP-64, that got worse over time. Yes, I was able to install more than 4 GB of RAM, which was the reason I got the 64-bit version to start with, but it just wasn't worth it.
I had no idea precisely how annoyed I was with XP-64 until I started using Windows 7.
For the record, I am using the 64-bit version of Windows 7 as well. But so far, not a single spontaneous reboot or any software that won't install. iTunes is actually on my desktop now, after three years of having to keep it on my laptop. But Windows 7 has a bunch of little nifty things that I am just loving.
The "quick-start" space at the bottom left of the task bar has been integrated with the display of active programs. At first this annoyed me (it is change, and change is bad). But now I love it. If you've got Firefox down there, for example, the first time you click it opens a new FF window, and the second time it just redirects the window focus to that program. If you want a new FF, you just right-click, instead, and choose "Open New Window". That's slightly more work than it used to be... but that right-click also gets you a display of frequently used links, and you can pin bookmarks to the display to open the site you want more quickly. This same functionality extends to any program you stick on that taskbar - for example, Excel. I have several Excel documents I refer to quite frequently (we have a budget, I have project plan for Alex, I have an idea list for Rebecca, etc. etc.). I used to put a shortcut to each individual document on my taskbar, or worse yet, go into Start->Recent Documents and hope that it was there. Now, I just right-click the Excel icon, pick the document I want, and launch it. It was a fantastic innovation that I had no idea I was missing.
Another thing W7 does that I've been waiting for forever is the ability to snap windows to the sides of the screen. I can just drag something to either side of the monitor and it snaps, so I can easily compare two documents, for example, or read off of one and type into the other. I have this humongous wide screen monitor and it's always annoyed me that I can't, in essence, use it like two side-by-side monitors. Now I can.
I've always been a Windows user, so forgive me if these features have been on Macs or Linux since the dawn of time or something. It's all just really growing on me, and I wanted to gush.