I recommended Mandriva for both newbies and professionals. Mostly updated than other distributions, great cooker repository, easy to install and use, well tested packages. You can try live cd version and install free version. To be honest, i prefer powerpack version which comes 3rd party software licences such as cedega.

On my home PC I use Ubuntu, with gnome. Really not my cup of tea as far as linux distros go, but it easy enough so that the wife and kids can handle it without running to me with questions every 5 minutes. It just works. With programs like cedega for games, and wine for apps, its perfectly adequate for everyday use at our place. Im even thinking of buying crossover so I can use photoshop and dreamweaver as well. Pretty well the only reason I still dual boot with XP.
On my server, I run debian 4.0, with fluxbox. But I rarely use the gui anyway, mostly for surfing the web and stuff. Most of my work is done through putty, as the command line is Sooooo much faster in my opinion. Deb based distros are where its at for me, dunno, Im just too used to them now I guess.
I started with red hat about 10 years ago, but when I got the hang of debian, I never went back.
Ive just got a 2nd box so now Im looking forward to setting up deb at home and letting the rest of the family use what they want, and they reckon theyre so used to ubuntu now, that theyre not interested in going back to windows.
I love linux.

I've tried at least 4 different distros. I first installed Ubuntu on my computer because I have heard it is good. I loved it and I thought GNOME was awesome. I tried Kubuntu through live CD to see what KDE was like and wasn't very impressed. I then downloaded Mandrake to see if my net could work with it. I wasn't to happy when I found out that it used KDE. Then I downloaded Linux Mint and installed that. Linux Mint is Ubuntu based, so it could use the Gutsy Gibbon packages. It also uses GNOME with the start menu at the bottom. I love it and I still have it on my computer. I have gotten the farthest with it to get my net working. So, I use Linux Mint and plan on staying with it.

Last time ago, I tried ubuntu distro..
unfortunately, my PC hardware is old..
I need to upgrade my hardware first before using linux distro for better performance.
So now, I am still using winXP for my daily activity.

A computer running XP surely isn't that bad. What's your ram amount and cpu speed? Off the top of my head, I would recommend VectorLinux or Damn Small Linux (In extreme cases). You can also get Ubuntu and install Fluxbox on it, a very lightweight window manager that will drastically cut down the requirements.

plez suggest me a linux with maximum hardware compatibility with latest hardwares, including nvidia and ati

There is no definite answer, but you should try Mandriva, Ubuntu, and Linux Mint.

I use Suse or Ubuntu for linux as well as Solaris 10 for my sun server. Whether it is Solaris, linux or unix they all have the same feel to it. Plus, there are tons of forums and users online in which you can easily get help from. Make sure you try the desktop cube since it is a very nice resource to have installed.

I prefer edubuntu for because its a fully loaded distro, with all the stuff i need (with the exception of audacity) But if I was talking about live CDs I would say puppy linux, because it's light, easy to use and i like it.