Mandriva definately if you want something noob friendly with all the functionality of Linux to get your hands dirty when your ready. Once you get the hang of URPMI you'll never want to look at an ugly Windows .exe ever again.
Great hardware detection though I did have problems getting my SB Live 24 bit to work at first but after a little coaxing she went fine. Suse 9.3 Pro is very nice as well but I spent way too long unchecking all the packages I didn't want during the install. All said and done I would highly suggest Mandriva.