The space you describe should fit a bigger case than the SG06, with a desktop (HTPC) case you heve a lot more options:ANTEC FUSION REMOTE MAX 19.05cm(H)
x 44.45cm(W) x 45.21cm(D) if you remove the case's feet it might fit, but I'm not 100% positive. This is the biggest case that might fit, full ATX, which gives you lots of options.SilverStone Lascala LC17
425 mm (W) x 170 mm (H) x 425 mm (D). Not as quiet as the Antec or as big, still plenty of room, full ATX, too. The front is aluminum, like the Antec, but it is available in silver, too.SilverStone Grandia GD05
,440 mm (W) x 150 mm (H) x 325 mm (D), quite favorably reviewed here
. Limits CPU cooler height to Big Shuriken, or Prolimatech Samuel 17 and fits mini ATX boards. GD04 is the Silver Version.Lian Li PC-C50
,(W) 445mm x (H) 167mm x (D) 325mm, quite similar to the GD05/04, accepts mini ATX boards. Does not limit CPU cooler height as much, a Scythe Kama Cross without the top fan fits
, the side fan blowing on the heatsink for cooling. Full aluminum construction, available in silver and black, light weight but expensive.
All of these cases accept a standard ATX PSU, which is the main reason to recommend them over the SG06. It comes with a mini ATX (SFX) PSU which isn't bad, but not great either in terms of noise.
I would use the Lian Li C50 and the system in the link for Scythe Kama Cross, just add the video card of your choice.
beQuiet! PSUs are not available everywhere, you can use an Enermax Modu 87+ 500W or Seasonic X-560, both are very good, get whichever is cheaper. Whatever you do, make shure to buy a modular PSU for use in a smaller case.