I think it will last awhile... I plan on putting another 6870 in it next summer along with a bigger power supply.
Also obviously the HDD, CD/DVD Drive, Monitor is missing from the list but I may just use them out of my XPS 420 unless I sell it then I'll be able to get all new stuff Think I could get $300+ out of it?
Gaming, 3D Engineering, Flight school (maybe), Video & photo rendering, 4-10 hours everyday use, I'm not a huge overclocker but in a few years that will change.
I'm really indecisive on some parts but the CPU I'm pretty sure on, reasons being I don't want to buy another new CPU & Motherboard in 3 years (8-Cores, OC it till it explodes), I'm not concerned with "Exact benchmarks saying This is better then That" more cores will always win in rendering/loading/ect, I can't live with myself knowing my CPU has the nickname of Sandy Bajina (no offense Intel lovers ).