Near about the most stable distro of linux that I have used is Ubuntu. It is the best for beginners coz it has a huge community where u find any and everything. It has wide ranged hardware support worked well on my quad core Q6600 . But u know its not the fastest of all. It easily mounted all my windows ntfs partitions in it. the 3d graphics worked well under compiz. Used wine to run win exe. worked like magic. But only some exe's work under it. Then there was an urge to shift to KDE. I liked it.... Though KDE4.0 is released .. i would not recommend to use it coz its very buggy at the moment... But the one with with KDE3.6 is stable nd a good distro but not the best as yet.