Well it sounds like you have plenty of storage to stream to your ps3. I know what you mean those power plugs ones are not too good.
You can stream on wireless quite good, depending on your unit/house. You said you had upstairs that might cause some interference. If you get a wireless access point or router that supports channel hoping you will get better quality. Channel hoping is when the access point detects interference it changes to a new channel automatically. They are a little more in price but worth it.
Another option is to build a cheap pc like I did and plug it via cat5. The ps3 supports giga LAN, I would get the local 40GB one over the import, the import is locked to what region it is for dvd's, the ps3 supports full upscaling of dvd's to the 1080p. So your normal dvd's look very nice on a lcd screen. There is no region crack at the moment so you will loose that function to be able to play region 3 HK discs. The 80GB model has the support to play older ps2 games, but when you get a ps3 you don't want to play ps2 games.
Blueray's are different they have region a,b,c and HK shares the same region as the states region a.
I got my ps3 from Star Star Electronics Sham Shui Po for $2680 (basic kit, one controller) and a Dual Shock wireless controller for $340. I found that place was the cheapest for pretty much everything to do with the ps3. I walked around the whole of Golden and got prices. Also you can get the ps3 at Broadway for $2680, which is the basic kit. So don't pay anymore then $2680. I also got the logitech bluetooth ps3 keyboard for $648 at Manic Sham Shui Po.
Also my cheap pc cost me:
Wisetek Sham Shui Po
$550 Dual Core E2160 1.8 intel cpu
$665 Gigabyte ga-73pvm-s2h
$150 Kingston 1GB DDR2 667
$573 320GB WD HDD (Kingsway Computers)
$245 Pioneer DVR-215 sata
$338 Antec Earth Watts 380 PW
$227 Gigabyte GZ-M1 M-ATX blk case (quiet)
That m/b is good for upgrading it supports a quad core cpu, it has HDMI build in and optical out, so if later I want to turn it into a full media pc I can. Just add some more ram.