k000 - I find Open Office to be frustratingly laggy. Don't get me wrong--it is phenomenal for a free piece of software. But, free isn't always everything.
From Newegg.com or Tigerdirect.com you can get MS Office 2007 Home/Student which includes Word, Excel, PP, and OneNote for about $90 for 3 licenses. I was using OOo until I saw that deal--$30/computer is a no-brainer for me.
And as far as PP goes, I think the real deal is much better than the OOo version.
All that said, I totally get the appeal of free (& open source) software...
Edit: And on SSD
space and processor usage, I would think space shouldn't be a problem for either. When I had a 16GB SSD
I double booted Ubuntu & Vista/W7 and had plenty of space on the Win partition for Office. And in my opinion, MS Office is snappier. I even use my Mini for PP presentations including music and animations.