Having made the jump to Linux (virtually alone) a little over a year ago, there's more than a few pearls of wisdom that I've learned here and along the way and would like to add.
So while this might be a vanity post, I believe there's a couple of pieces of "food for thought" that people considering Linux should take into account.
Call me a little biased, but I personally recommend Suse to new Linux users. However, Fedora and Mandriva are also very good choices.
Of course, it depends a lot on what you plan to use Linux for and the experience you have with *nix systems. For example, it's not very likely a person who's always run Windows to install and run Gentoo, BSD, or Slackware.
Many people want to keep a dual-boot running--for whatever reason. I've personally found that using a distro with a graphical installer makes it easier to resize an existing (most often, Windows) partition and enable both OSs to boot correctly.
Another thing is to keep in mind other users. Example: if you're the only one who's comfortable with *nix, it's not always the wisest option to run a more advanced distro. Many people simply require a smooth transition as opposed to a steep jump (think the old phrase "baptism by fire").
I personally don't like dual-boot b/c I tend to stay with one O/S. I prefer virtual machines and now that Xen is packaged with SuSE it should work out fine.
Congratulations on the switch and thanks for the feedback - it's always helpful to hear what others are doing.