I have done it on a 3.2GHz machine with 512mb of ram and a 6 meg connection to the internet, I did a live installation, basically the compilation of the base system took me about 2 hours and that is including the manual compilation of the kernel, the long ones where.. Xorg which took about 3-4 hours and then either gnome or kde which either take approximately 3 hours depending on the system, the weeks thing is a myth its only for people who can;t get it together... and by the way it is worth it because Gentoo is the only distribution that can be tuned all the way down to its roots, so don't be afraid to install it, My suggestion is that you follow every little thing in the manual especially if it's your first time. Good luck.