Well my favorite so far is Ubuntu, I'm gonna try out Kubuntu, Xubuntu and Edubuntu (I'm trying to learn about thin clients) also I'd like to see what BSD's like. Don't use RPM, it's brain damaged. The worst thing though is that I can't keep up with the updates (I have shitty internet service and there's nothing I can do about it for about 6 months, that's why I'm so pathetic), but at least I can get the CDs for free.
Basically any of the desktop managers can be configured to look like Windows (depending on your skill with theme package editing), but KDE is setup to look sort of like Windows as default, and comes with a theme "Redmond" to make it look even more so if you like (I find it quite ugly). Also KDE has a few neat ways you can waste your CPU cycles with nice graphics (like a certain OS I recall).
If you want a more efficient setup you might want to look into lighter WMs like XFCE.
As for hardware, for a workstation or server you should be covered whatever you choose. With laptops, its not so easy. Ubuntu is one of the best for laptops, but you still should look up whatever you can about your hardware and base the decision on that. My laptop (a 1 year old Toshiba that's falling apart) works fairly well on it, with the exception of power management, which is not supported well at all (I haven't tried Gutsy yet).
Don't forget to download the latest version of WINE, it can be very useful for some Windows programs. If you're made of money you could look into products like VMware, Cedega, and Crossover. Or if you're an uber-geek there's QEMU which is free (but not easy to use).
You should set up your machine to dual boot, otherwise you'll go crazy during the transition. I've been using linux for a long time, and I'm pretty experienced now in shell scripting and setting up servers and system stuff (and other stuff you won't need to know unless you really get into it), but I still use Windows a lot, actually I switch between the two depending on my mood and what I'm doing. At least whenever MS finally does something to really piss me off (or if they go bust, yeah right), I'll be ready to jump ship, before it sinks.
Regarding editors, use whatever you like, I don't want to start an editor war
. Vim (and workalikes) can increase productivity a lot if you get used to it, but its not for everyone.