It's a new operating system with massive improvements in numerous areas. Mostly networking and security.
Now, I do not want to turn this into a Mac vs Linux vs Windows issue, but Windows has always had better inherent security functionality than Linux, albeit a terrible default configuration. Windows is of course a microkernel, and has a true reference monitor, unlike the UNIX like operating system which must rely on non-tamperproof modules to provide reference monitor functionality, which defeats the purpose of having a reference monitor. Along those lines, Windows has far better file permissions, and now has an integrity control system that utilizes a modified Biba model. XP lacks the integrity systems.
Windows 7 is what Vista should have been. It is a lightweight operating system, easily comparable to Linux in terms of resource usage (other than hard drive space) with equal environments and features. This means a fully functional desktop with fancy effects and everything else. We all know a CLI slackware install is faster than Windows anything when it comes to responsiveness.
Disk operations have been optimized, although that heavily depends on the file system used and whether you have a 64 bit os. Windows 7 handles large files better than Linux, with Linux doing better on smaller files.
The entire device driver system has been changed, mostly for the better. This has always been an issue with Linux... good luck getting your webcam to work, or most little extras like that. Have fun syncing your BlackBerry as well. Obviously, the only way this is going to change is if OEMs start supporting Linux more than they are now. Obviously, most of the larger OEMs already support Linux. I'm not worried about my Cisco wireless card, I know that always works, where's my webcam? Why doesn't my fingerprint reader work? I can't get my scanner working... Linux is not going to be a viable operating system for home users until you can buy something at Wal-Mart, plug it in, and have it working like you can with Windows (most of the time.)
Obviously, Linux has a few areas it does better. PAE is a big one, although there is really no reason not to use a 64 bit os anymore, so that may become a moot point unless you have some older software which will not run in a 32 bit compatability mode. I also prefer a bash prompt even over Windows PowerShell.
EDIT: Carling, once again, you fail to comprehend. I said 2.6, not .26
You still can do nothing more than quote statisitcs and market trends rather than give a single example of a technical issue. I describe functionality, you run to irrelevant netcraft surveys. Your methodology is based on the assumption that market share and random statistics have any bearing on the operating systems themselves. I'll put it into a non-technical example. I have two cars parked in fornt of my house right now. A 93 Ford Taurus Wagon and a 2007 Mercedes C320. If we look at the "numbers," then the Ford wins because it is obviously more popular. Is it safer? No. Is it faster? No. Is it more efficient? No. Is it even as comfortable? Hell no. Your numbers would still show the Taurus to be superior. If you want to talk security, why aren't you throwing Trusted Solaris, GEMSOS, or any other high security operating system into the mix? I know the answer, you're essentially the foreign version of Geek Squad, just rehashing any random statistic that makes you sound good without any understanding of underlying functionality or design. I can give out statistics that "prove" anything I want. You'll throw different statistics back proving your point. Without actually comparing the systems side by side, no statistics matter. If you see that operating system A has ten vulnerabilities this year, and operating system B has twenty, you cannot actually say that B is less secure. The number of vulnerabilities is irrelevant. It is the design and functionality of the system that gives a real administrator the ability to mitigate vulnerabilities without ever having to patch, and the ability to contain and prevent intrusions be they automated or intelligent. I bet you actually believe that chrooting is some sort of security measure. It's not. It's a restricted environment that still allows me to grab execv and break out of the jail. Linux does not even allow for the granular process ACLs that can manage and defeat memory leaks and many buffer overflows at the system level.
One last thing, the kernel you mentioned... If you had any enterprise experience, you'd know that in any high assurance environment, or even a basic enterprise environment, the term RC1 is nowhere to be seen. Release candidates simply do not exist.