Those risers look the pretty much the same, but maybe someone with experience using risers can chime in.
As for that XFX power supply, all I can say about XFX is that of my only failures in the last two years, it was XFX. I found one review for their 1250W model, and it seems decent. It's on a Seasonic platform, but it's multiple rails instead of a single rail. The power supply is one of the most important parts in a mining rig, and the Cooler Master V1000 is only $30 more even after XFX's rebate.
Ok ok your right I shouldn't skimp on the most important part of the pc. Bronze version is $45 cheaper than gold. Since this is a trusted brand is bronze certification good enough or pay the extra $45?
http://www.amazon.com/Cooler-Master-Silent-Pro-RSA00-AMBAJ3-US/dp/B002RWJGCM/ref=sr_1_2?s=electronics&ie=UTF8&qid=1374021819&sr=1-2&keywords=Cooler+Master+V1000Edit:
After thoughts are these psu's going to fit in the case? Currently have a 750w installed without much room for improvement.
How do the cards run without plugging into a screen?
That looks like a decent model, less top-of-the-line components and older than the V1000. Gets better user reviews than the XFX and I'd trust it more. But I think the better efficiency of the V1000 will pay for the increase in cost over time in saved power (from reviews, on 120V it looks like you'll only get a bit better than 80% efficiency with your rig, whereas the V1000 hovers around 90%). So frankly it's up to you.
And, yeah, if you're putting this in a stock HP case, good luck... not only will things be tight, cooling will be hectic. You may want to consider an open air setup or get a better case. Honestly I can't even imagine trying to cool a rig properly inside any OEM case.
As for a headless mining rig, I believe it's been posted about before. For Linux, it's pretty easy. For Windows, I think you still need dummy plugs.
I think you may also want to ask yourself if mining is right for you. There's a lot to know and a lot can go wrong, and it's barely profitable right now for scrypt coins anyways. You may end up spending more than you'd like to do it right and not come out ahead.
EDIT: Actually checking out the reviews it seems the cross-load stability sucks for that Cooler Master model. While probably not going to pose a problem, I'd shoot for the V1000 knowing that and the better efficiency.