First off, why are people even mentioning software in STORES for Linux? Everything for Linux is free (unless you purchase licensed commercial copies of sUSE or some other distribution like that). All the software that you will have available to you will be listed in the Adept Manager (in Ubuntu... I believe it's Yast in sUSE and called other things in other distributions). Tetraca is very right on needing an Internet connection to get things working... most likely a hard-line connection, since some wireless cards are still not supported ON installation. (But with programs like Ndiswrapper and WICD, connecting to your wireless network is a little easier with a bit of work.) With an Internet connection, a wealth of FREE software is at your fingertips. Why spend $100 on Microsoft Office, $600 on CAD software, $300 for Photoshop, 3DStudioMax, or anything, really, when you can get equivalents for free? (I'm talking about OpenOffice, TurboCAD [?], GIMP, Blender, etc.)
People are turned off by the idea of Linux because it immediately brings up the idea that it's geared more towards the technically-proficient (i.e. geeks). Another obstacle that most people won't bother with is the fact that they'll have to learn another operating system.
I just jumped back into Linux not too long ago with Kubuntu 7.04 (Feisty Fawn). I tried upgrading to 7.10 (Gutsy Gibbon), but I love my eye candy and Compiz was just not working for me, so I downgraded simply to have a working version of Beryl.

(Oh, and by the way... I think that Beryl/Compiz is much better than Aero. It's almost like a combination of Aero and the eye candy effects of the Mac OSX interface... I think.) In all reality, Linux is designed for familiarity from other operating systems, depending on which distribution you decide to install. I'm personally happy with the look of Kubuntu, which almost mimicks and betters the Windows interface, whereas Gnome has more of a Mac feel (that I didn't like as much).
If you actually take the time to look at the operating system, you may find similarities between your current OS and your Linux distribution. In the case of Kubuntu, Add/Remove Programs is accessed by either the Adept Manager (a more advanced version) or by Kubuntu's own Add/Remove Programs interface (a GUI version of the Adept Manager). KNetworkManager or WICD replaces the Windows Zero Wireless configuration; the Start menu is the KDE menu; the taskbar is still there, but you can customize it so much more to your liking; you can personally skin just about anything in Kubuntu as opposed to Windows' limited options; and all the program support is there, including Wine, the Windows program emulator. (If it seems like I'm comparing Windows to Linux, I am... I'm not familiar enough with Mac OSX to make much of a comparison.)
Linux, in my opinion, is good for basic use (i.e. Internet, word processing, image editing, listening to music, etc.) as well as the advanced (i.e. CAD work, programming, etc.). Game support, however, is lacking in the aspect of the latest and greatest that we have for Windows (games like Call of Duty 4, World in Conflict, Crysis, etc.), as is Mac OSX. (I'm not sure what game developers have in store for Leopard.) Linux provides its own share of OpenGL games that will not blow you away as far as graphics go, but they can be as fun and addicting as Flash games online. (They also have a sort of charm to them too.)

Basically, I would recommend Kubuntu to anyone looking for an operating system that is flexible and able to do anything but play games... which will turn off most gaming enthusiasts, but rumor has it that there is an answer to the DirectX compatibility issue that keeps gamers off of the Linux operating system.
The largest appeal to Linux will be its flexibility and being able to tweak it to however you want your operating system to look and function. Another large appeal is that it is free as opposed to having to fork over hundreds of dollars for Windows Vista and Mac Leopard (which are ridden with problems... it doesn't "just work" now, does it?). For a free OS that works and that caters itself to however the user wants it to, it's worth a look.
And keep in mind, I am a Windows user primarily but starting to play around more with Kubuntu. Each operating system has its pros and cons and I like Windows XP SP2 and Kubuntu Feisty Fawn, which is why I dual-boot.