I'm an audiophile and a real computer dealer with full a scale service dept for a large account base and have used the Infrant ReadyNAS, now owned by Netgear, running Linux at the NAS level and Slimserver, (now called SqeezeCenter byLogitech), with 4x250gb at my home and have one installed at a friends home. They are very quiet, reliable and have had absolutely no tech issues. I can not speak of the speed for video apps, but mine had not trouble sending 3 different signals to 2 Wifi, and 1 wired player at the same time using flac files. I also had no issues with my photo collection being stored and retrieved....( 12-30mb pics ). I have since given the ReadyNAS away to an employee and upgraded to an older HP Proliant Server running Win Server and supporting a pack of 300gb 10k drives in a raid system. My motivation for the change in configuration was the speed of indexing music and how long the application took to refresh, and searches for music. I believe this had to do with the Linux OS and SqeezeCenter running at the NAS level and not the Server or PC level. The difference was night and day, and worth the expense for my level of patience. The music of course didn't sound any different nor was the performance any better once a file was chosen. I would just get frustrated waiting for a new page to load when browsing. Downside is the noise a server makes..(mine in a remote part of my house thus not an issue), and the added overhead of Win Server and needing the tech ability to maintain it....obviously not a plug and play solution.
The entire project was very worth while for the reason that now my children have access to, and are influenced by my music collection and not reliant on their peers for new music...Example my 10yr old daughter listens to as much 70's rock as she does whatever that thumpy crap is she listens to the other 1/2 of the time.
Don’t know if this helps you any…but is my story to finding a solution that worked for my household.