I'm not sorry for the downvotes.
-a- There is no "Linux Desktop", only "What I want my desktop to look like". If you want decisions made for you, there are alternatives. Linux-with-a-GUI ain't one.
-b- Sensible replacement for Outlook? Mutt. No, thats not a joke. You don't agree? Thats ok. To me, mutt handles mail in such a spectacularly better way than Outlook I wince when forced to use the MS "mail client" (hello? Doesn't even handle adressing right?) You might be looking for decisions to be made for you again. See -a-.
Linux isn't, never was, and despite the work of Gnome et al, never will be a drop-in replacement for Windows. If THAT is what you want, you can save yourself a lot of trouble by looking elsewhere. Telling off DeLorean 'cause it's a poor substitute for your stationwagon isn't productive.