First, Linux will do about everything, if one doesn’t need specific applications, like the latest version of Photoshop. For the basics, it’s perfectly capable of holding it’s own with any OS.
Second, when someone begins using Linux, I recommend a few things:
[1] Dual boot. Keep the old stuff about while you learn Linux. Never run the system as root. Get used to Linux slowly, on your own time, and don’t try to impress your friends…you will break things, and be embarrassed and frustrated.
[2] Just use what comes with. Install the security patches the OS offers in the auto update application. Don’t start upgrading, tweaking, and installing stuff right away. Don’t even attempt to compile software from source. You’ll probably get yourself into trouble. Don’t try to impress your friends; you’ll get frustrated.
[3] Don’t try to get 3D acceleration and fancy desktop transition effects working. They don’t make Linux one bit more productive, and they will get a noob into trouble a fair amount of the time. Don’t try to impress your friends.
[4] Read, read, read. Browse Linux forums, wikis, books, help files, man pages, etc. and read all you can. *nix systems are significantly different from Windows. Leave your Windows expectations for when you’re running Windows.
[5] Learn about the *nix file system and security. Knowing where things go, what resides where, and what root/normal users can do is a huge step towards mastering Linux.
[6] Ask questions after you’ve researched and done some work on your own. First, you’ll likely get more and better answers when people see you’re willing to put in the time necessary to learn. Second, you’ll have a much higher probability of understanding their answers and being able to use them.
[7] Always back up your data/configuration before you try anything new. If you’ve done (5) you’ll know what to back up.
[8] Learn how to use a shell and console-based configuration utilities, including changing config files with a text editor. If you know how to use console-based utilities when things go wrong, you’ll very often be able to fix whatever broke.
[9] Understand you’ll never know everything, but you will get to where you know enough, if you persist. Enjoy the freedom and flexibility of Linux. Recognize that it moves very fast, often too fast for stability, and often holding back will help keep your system running. Don’t get religious about any OS, it will just get in your way.
[10] Tweak, break, and learn more. The last step. Do all the stuff I cautioned you not to do above, except running the system as root, if you want. You’ll get to where you’ve got the right mix of tools and experience, and you’ll be able to fix what you break. This is the good part. ☺