Actually there are more like over 300 Linux distributions in active development, not that that helps alleviate your confusion. ;) Of course the number that are widely known is much closer to your estimate, give or take, depending on how much you follow Linux.
After wearing the wheels off my beloved Windows 2000(due to an idealogical aversion to XP's requirement to "Activate" a product I paid for) I switched over to Ubuntu Linux back in 2005 and have been using it full time since. Its mature, and fully featured. All the eye candy of Vista, if that's your thing, mature and effective security and user management, and tons of free software to do just about everything you need a PC for. Oh, and the OS itself is free, and updated every six months with a brand new version.
Sure, Linux has its limitations, but most have at their base that its not Windows. ie. Gaming: Quake4 and Quake Wars run natively, beautifully, and likely better than they would in Windows due to the lower OS system requirements, but playing Half Life 2 requires tinkering in WINE, and then there are some games that are just going to be a complete no-go. Admittedly, thats a hassle. On the other side, the games that are available are startling in their number and quality. My son is currently hooked on TORCs, a racing simulator.
As for the non gaming utilities, like I said, you can do pretty much everything you want, and probably for free. With modern distro's such as Ubuntu and Fedora, the learning curve for running a desktop linux system has been tremendously flattened, and is now, IMO, equivalent to a new computer user learning XP from scratch.
and if you compare the Linux learning curve to Vista, it is probably less.