HTPC Set up advice?

Hi all im pretty new to all this and could use your thoughts and advice...

here the set up im considering for my HTPC...

A Zotac Zbox Id41
http://www.ebuyer.com/398176-zotac-zbox-...d41-plus-b

with an additional 2gb of RAM installed, bringing it up to a total 4gb.
http://www.ebuyer.com/159916-crucial-2gb...5664bc1067

I went with this zbox with the thinking that the Nvidia ION chip would handle most media thrown at it, but my main concern is for smooth play back of 1080p HD mkv files and streaming media. Your thoughts on this please?

I plan on installing XBMCUbuntu, however iv heard OpenElec is good. Which should I go for?

Also any thoughts on a remote? iv heard all MCE remotes work well with XBMC.
I plan on using my smart phone in the mean time, any one tried this?

Any other advice is welcome. thanks!