There isn't any reason why Sabayon (or any other modern distro for that matter) shouldn't run on the above listed hardware - but one of the wonderful things about Nix is the LiveDE boot from the disc and try it out, if it works then install it
Personally I prefer Gnome but your desktop environment is really a choice you need to make for yourself, if you have bandwidth to burn try downloading each of the discs and seeing which one you like more. At any rate I see both your systems have 64bit processors so you want the 64bit discSabayon 4.2 64bit Gnome isoSabayon 4.2 64bit KDE iso
Also if you do choose to install Sabayon, don't make the same mistake I did the first time around - be sure to read this VERY helpful page
on how to get your system updated and fully working. Its not as straight forward as other distros, but if you follow the information listed its not hard.
Sager NP8662 - 2.8gzh p9700 - 4 gigs DDR3 - nVidia 260m - 640gig HDD - Linux 32bit