Do you really need the DVI-> VGA adapter? Sapphire's brochure says that the package includes this (as has every videocard I've ever bought, I have about 10 of them floating around here). Of course it is only $3 and I could see being annoyed if the card didn't come with it and that held you up.
I don't know anything about that particular power supply, but it's a respected brand just not a model I've heard discussed. Your system doesn't seem overly PSU taxing so it's probably fine.
For video editing you might want an additional HD, as that can take up a lot of space. The Seagate and Western Digital 250 & 320 GB SATA drives are under $100 on newegg if you want one. That's also something that's easy to add later when/if you fill the Samsung if you don't want to get another HD now.
That RAM looks like a great bargain. Might have to get some myself...
Great ram choice instead of *cough* overpriced xms *cough*.
The Fortron has just enough amps - 30 to be exact for a full x1950gt pc build. Wattage shouldn't be the focus these days as many of the big psus have more than enough wattage to power modern videos, the focus should be amperage. If the video is upgraded, it MAY not have enough amps, depending on the video card.