Stefan,
I'm not sure from your post whether your plans are to continue working solely with DV video or whether you have some plans in the future for HD formats.
In any case, I think that you would be much better served by making changes to both your hardware plans and workflow more along the lines of the following:
Single 128GB Samsung 840 Pro (don't get the std. 840, its writes are much slower) - OS/Programs; if you turn off the hibernate feature 128GB should provide plenty of space
Two 1TB 7200 rpm drives and either spread the load (projects and media on one and scratch / cache / outputs on the other) or RAID 0 them and put all files on the RAID array
Do nightly backups of media and project files to your DS111 (orgainze your directory structure so scratch, cache, and output files can be easily ignored from the backup)
This plan with give you way more speed and improved redundancy as well (as the DS111 is only a single drive unit).
With your new faster system you would probably enjoy using the local drives for photo editing work as well, especially if you go with the 2x RAID 0 array option.
Finally, you should probably increase the RAM of your new build to 32GB; what Windows 7/8 does not use for programs is does use for disk caching and that tends to speed things up for photo and video editing workflows.
Regards,
Jim