WHS and Media Streaming

I know there are quite a few threads out there regarding this topic but none I feel that really address a core issue I'm struggling with. I love WHS for what it does, in managing most of my data, expandability, etc; however, wrt streaming media (particularly video) to several XMBC clients in my home, the performance is choppy at best to the point where its just not a viable solution.

I have and have previously used a Netgear NV setup (with some form of RAID5), and streaming worked fine, with no stuttering. But I wanted to get through the capacity limitations on that box and built a custom Norco 4020 rig. I reused a lot of components from my old box. Otherwise, I would have gone cheaper, most power efficient.

Componentry:

Norco 4020
EVGA Nvidia 680i MOBO with 6 SATA controllers
Intel Quad Core Proc
1000w PS
8GB RAM
Highpoint RocketRaid 2310 (4 sata controllers)
2 Gigabit Adapter

I'm trying to stream ISOs and AVIs. Some people have said to put my video in a better format, but I've heard quite a few folks that have successfully streamed BluRay ISOs from their WHS box.

I took one of the drives out of the WHS managed space and tried to see if I could increase performance this way by taking it out of the balancing mix. No dice.

I'm thinking I might need to get a better RAID card, and stripe some of the drives outside of WHS, on a separate RAID channel, to serve my video?

I really want WHS to work, but ultimately if it can't stream media then I'm going to have to look at other solutions (e.g. UNRAID, FreeNAS). Albeit, I don't necessarily want to go down that path as I'm not a linux guy, and frankly like the other disk management capabilities of WHS.

Hopefully someone "feels my pain", and might have some insight.

Thx.