wich distro. is the best for beginner like me?

There are tons, but the answer is "it depends". Do you have an extra machine laying around? If so, I'd just pick one of the top 10 from distrowatch and try installing it on that old machine.

If you only have a single machine, I'd play around with Live CD's for a while to get used to linux. Then I'd try installing something in a dual boot so you could still go back to your old operating system.

Each distro has strengths and weaknesses. So it depends on what you're trying to do with it...

ok, now iam using widows sp2 and i hate it becuase of its viruses and problems. iam just a simple user so I want a linux disro. compatable with my needs (games&multimeadia programs&etc)

Windows games typically don't run on linux without some work (though some have linux ports and others may work with Wine). There are some great open source games for linux though. Multimedia works fine once you install the correct codecs. Basically any of the majors probably will work fine (Ubuntu, Fedora, Debian, OpenSuse, Mandriva, PC LinuxOS, Mepis, etc).

Again, you can try downloading a live CD/DVD and just run it to see how you like it. Just keep in mind that you're probably going to have to relearn some things because linux is different than Windows.

Try taking the "Linux Distro Chooser" quiz in my signature.

This is a good read for someone moving across: http://linux.oneandoneis2.org/LNW.htm

The best distro (for you) is often simply the last one you try. Pick anything in the top ten at Distrowatch and dive in.