Processor is ok, unless you want to do Supreme Commander like games with loads of AI in it and a core maximizer on. Then I would recommend a 4 - core processor, but otherwise this proc. is just fine.
I wouldn't bother too much about the mainboard. You won't notice any performance difference for the things I guess you will be doing. Important here is:
- do you want to upgrade to a dual graphics card setup later perhaps?
- do you want USB3 support built-in (makes quite a difference if you have a USB3 stick / disk)?
- do you want SATA 3 support built-in (great for the latest SSD disks).
- will you ever want to put your Pc in a small cabinet instead of a large one? then pick a mATX instead of an ATX.
4gb of memory is just fine, but for future apps etc. you might consider putting in 8 giga's
. Prices are very low a.t.m. for DDR3, here in Holland 8gb will cost you 34 euro including delivery, so reletively, that's just peanuts.
Like HT said, 60gb SSD will do for booting and a few games or apps that need the boost. Other than that, you could go for a 1TB (non-ssd) disk, or perhaps instead of both a 512gb hybrid disk. Keep in mind, non-SSD disks are very expensive a.t.m. because of the weather issues in the east.
5670 is ok for gaming, but I'd go for a 5770 or a 560ti like HT said. I used to own a HD6870 and that one is also perfect for your needs.
One final tip:
* Second hand isn't bad! When I want a new processor or memory, I always look for that second hand! Those are parts that will last long usually. Only be carefull that the processor hasn't been overclocked (too high / too much).
Good luck!