Your system looks fine, and always go with the fastest video card you can afford. You will also want to add a bluray burner. And NO RAID, instead install all software on 1 drive, and store your projects on another. If you can afford, go with 1tb drives, as HD video fills drives quickly.
But just as important are these pointers:
* Fine tune the system when you get it. Any system (other than home build) is bloated with junk software, and Dell is no exception. Uninstall it.
* Fine Tune W7. There are numerous articles on how to do this.
* Update all your hardware drivers, including video. You would be surprised how old the drivers will be on a new unit.
* Don't install general use software, leave the system as a video processing system, with only the software you need for the specific NLE you chose. For PD10, you will need the latest version of quicktime. Install that BEFORE PD10
* Install PD10 last, after all other software, and after all driver updates. To avoid sodftware related issues, follow the "specific" install instructions on the PD10 forum here: http://forum.cyberlink.com/forum/forums/show/99.page
Read up a bit, while waiting on your system to get here.
* Don't install the PD10 "demo" on your new system. But DO install all PD-10 patches, as per the instructions on the forum.
* Use an antivirus that does not use a lot of resources, such as avast. But turn it OFF, when using PD10. Also disconnect your network cable when using PD10.