I want to use this server as my desktop as well. My desktop usage is mainly for internet browsing, checking email, playing videos and music....
Personally, I would separate your desktop usage from your LinuxMCE setup completely. A laptop/ netbook or dedicated desktop machine with your chosen OS can sit on the linuxMCE network, connect to the media shares on linuxMCE and be used to connect to your core/hybrid and do administration etc but separate machines works better for me for the following reasons:
* Your desktop requirements are not dependent on your LMCE server being up and available. I don't want to make it sound as if the system is unstable because it isn't and my core has run for months on end many times. The issue is the human! You will find yourself wanting to tweak and fiddle once you realise the capabilities of the system. When you do, it is good not to have your desktop (email, web browsing etc) requirements interrupted when you break something.
* And then secondly, I personally have found the KDE desktop running on LMCE particularly slow for some reason. I've only used them on media directors, not on a hybrid but still, that has been off-putting and I try to avoid using it.
* Thirdly, you will obviously be limited to Kubuntu 10.04 (at the moment) as your OS/Desktop of choice and certain software you will not want to upgrade/ change or they might mess with you LMCE setup.
Those are just my experiences with it, others may find differently.