ok - I was more looking to get into larger drives, as XP doesn't like a single drive over 2TB (though there's a workaround)... I actually have one of the HP home servers and was considering consolidating that into a new sage box - I have way too many computers around the house that are always-on. Just for the two of us, we have my desktop, wife's desktop, livingroom PC, WHS, and yet we still do 90% of our computer-work on our laptops... I don't want to push my luck with Sage's reliability, but wouldn't necessarily mind ditching the livingroom PC and the WHS for a single machine who's primary goal is Sage.
I'm also having a hell of a time deciding on a case - but I think I'm putting too much into this. All the cases I see and like seem to be for 12x10 motherboards - I'm not sure how common those are or if they're often larger. For mobo, I was considering something like an Intel or an Asus (total lack of knowledge on home-built machines - I buy all corporate-type prebuilt machines/servers) - and probably a single quad-core processor and about 4GB of RAM... Hardware RAID, some half-way decent dual-head 256MB radeon video card (pref/ w/analog& dvi), gigabit ethernet, blue-ray reader, and the ability to add 6-8 drives - potentially hot-swap w/hardware RAID - and in a 4U rackmount configuration (so they can have bigger, quieter fans)...
First priority is Sage - second is other media storage, 3rd would be WHS-style home backups, and 4th would be the ability to use for web-based baby monitor or a quick internet browser on the big TV... 2,3 and 4 are nice-to-have's, with Sage being the requirement - and I wouldn't want to sacrifice stability in any way (I know enough to not get viruses, etc). Also, (5) would be nice to be able to rip and playback my DVD's straight from that machine, but that follows the same rules as 2-4. I think I'll order my case & hdhomerun today, and kick around the mobo part - I can always go to Fry's for those parts if necessary.