I've actually loaded and fooled with some of the distros lately. If you are asking the questions you are asking then I would avoid things like Gentoo and Slackware. Stick with the "plug and play" graphical distros. Here are some basic observations.
Fedora 10 - a very good and sophisticated distro. It connected to my network easily. The add/remove software and repository system is complete and easy to use. I was never able to get the thing to play videos. I spent 4 or 5 hours fooling around with codecs and media players and finally gave up.
Open SuSe 11 - I can say about the same things that I said about Fedora 10. One nice thing is that, if you get the DVD version you get both Gnome and KDE desktops so you can load it up either way. It is tied with Fedora 10 in my opinion.
Ubuntu 8.1 - 9.0 just released but I've only tested it with KDE so I'll just comment on 8.1. This is probably the best all around "plug and play" type distro. I had a horrible time getting it to connect to my network. I finally had to load and install SMB4K which is a share browser for KDE into my Gnome desktop. That finally allowed me to connect to my network and mount all the volumes. There was no way to do it either manually with shell commands or with the normal network connection packages. No other distro has given me this kind of trouble with my network. I'm thankful SMB4K did the trick. No problem getting Ubuntu to play videos like the other two distros above. I just downloaded a recommended codec pack and it worked like a charm. Very nice collection of packages included on the DVD version and the repositories are probably the best in the business.
Linux Mint - Based on Ubuntu 8.1, it is pretty similar but actually has some nice utilities that work well for a Windows user. I would view it as a beginner version of Ubuntu and shares the same comments. It has a more limited collection of packages but they can be downloaded from the Ubuntu repositories just fine.
Debian - I have a perfectly good working DVD with Debian but it won't install on my new technology computer - Intel Core 2 Duo 3 Gz with a Sapphire ATI 4550 card - ASUS P5QL mainboard. It goes "out of range" and the installation freezes. The "plug and play" distros all load fine on my Core 2 Duo system except for Mandriva which seems to be as fussy as Debian. Debian loaded fine in my AMD quad core system but, obviously, it is fussy about hardware. You may want to skip it unless you have a computer that is a couple of years old. The distro itself is actually pretty sophisticated. You can install it manually or automatically as you see fit. An example of its sophistication is that the automatic installation allows you to do custom drive partitioning, something that is usually only available with manually installed distros. This is the grandfather of many other distros including Ubuntu.
Mandriva - Same installation problems. Fussy about hardware.
Slackware - See Madriva above
Gentoo - See Mandriva Above
Scientific Linux - This is based on the Red Hat commercial distro and behaves very much like Fedora 10 except that it is not as sophisticated or complete in terms of the packages included. They can be downloaded from the Fedora repositories, of course. Basically nothing there that Fedora 10 won't give you and Fedora will always have newer releases that Scientific would need to catch up with.
