I've been using it for 3 years now. Long ago from kernel 2.2.27-rc2. I know its funny why I started using linux on a release candidate. But, I always want the newest.
Linux is really different from Windows and little less different from Mac. Mac is also derived from a Unix version. Its an 80's kernel and as far as the kernel goes, Linux is better than Mac.
Linux is insanely reliable. You can run it for years without crashes or freezes. Its very advanced unlike Windows. But, if you wanna start, I recommend installing "Ubuntu 8.04". Its easy and has big community support.
I usually use Slackware or Arch bcuz it gives me more control when it comes to managing my resources and doing network experiments. I've 2 systems so basically, I always do hack games through LAN.
Linux has this very powerful thing called Shell or maybe terminal. Its like command prompt buts 100 times more advanced and powerful. You won't start appreciating Linux until you mastered the shell.
Sorry for going off-topic. Anyway, Ubuntu 8.04 Hardy Heron is really good as its use friendly and makes the conversion from windows to linux easy.
After installing, go to "Applications --> Add/Remove Programs" and search for VLC Player or Amarok to play Mp3. If its not playing, you can search for "codecs" and install it to play them. Install Real Player to play rm files. (In mine, Totem movie player which comes preinstalled plays rm).
Pls don't hesitate to ask me about any doubts.
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Happy Independence Day !! 62 Years of Glory !!