The RAIDwill be of use in media editing / conversion but won't help with the gaming end.
Hard Drives - Check out the performance charts and pick whatever 500 GB per platter drive performs best under your usage patterns. The WD Black 2 TB is a good choice but at smaller capacities, you are limited to the Seagate 7200.12 or the Spinpoint F3. The 7200.12 excels in gaming, multimedia and pictures whereas the F3 wins at music and movie maker. See the comparisons here (copy past link in manually, link won't work in forum):