Do you remember what you had to do to learn Windows? Same concept. If everything in Linux was the same as Windows then it WOULD BE WINDOWS! Expect a learning curve.
No, it won't erase all your stuff unless you do it wrong....just like doing something wrong in any OS would erase your stuff. Now, just to let you know how MS operates..... If Windows is on your hard drive and you install Linux, it (Linux) will play nice and gently make room for itself AND WINDOWS and all your files! If, however, Linux is on your hard drive and you try to install Windows.........guess what? Windows will wipe Linux AND all your files off the disk! That ought to tell you everything you need to know about the MS corporation.
Try a LiveCD first. This procedure will give you a taste of Linux without touching your hard drive / files and will tell you if Linux will run on your hardware. Remember that it's going to run slow b/c it has to be uncompressed on the fly and loaded into RAM.
Most MS products, filesystem and formats are NOT compatible with Linux. Having said that, you can run many Windows applications and even Windows itself in a virtual machine or an emulator like WINE but it is not recommended for newbs. The problem with doing this is that you are still dependent upon the product that is causing you to consider switching in the first place...........makes no sense.
If you are running a business and HAVE to deal with clients who use Photoshop, Quickbooks and AutoCad its going to be tough, but for the average user and even some enterprise situations, there are plenty of opensource apps that have similar functionality to these proprietary apps and in some cases have features that even surpass those commercial offerings.
My recommendations for full featured distros: PCLOS, Mandriva, Ubuntu, CentOS, Xandros (if you don't mind their "relationship" w/ Microsoft). I have mixed feelings about Suse, Fedora but some people swear by them.
lite distros for less powered PCs: VectorLinux, Puppy, DSL, SAM Linux ( these distros use a lighter desktop environment that may be unfamiliar to new users)
other good distros but not as mainstream: Mepis, Sidux, Kanotix
hope this helps.
Edited by Trio3b, 19 June 2009 - 12:03 AM.