First, congratulations on selecting a great motherboard. I was doing research on it and even though it isn't the newest out there it is loaded and can do Crossfire as well (if you can afford it).
1. You have several cpu choices.
2. You can easily upgrade to a better video card.
3. It is stable and as I said it is loaded.
* I went to Gigabyte's website for your particular mobo specs and they list your slots as 1.8v so what you were told is correct. A shame too because those sticks you have now are really good memory.
* In my research over at Overclockers forums I looked at several people's rig set-ups and paid particular attention to the power supplies that were being utilized. They ranged from the 600w to the 700w.
I went to NewEgg and I believe this one will do you very well; it has excellent reviews, nice price, great performance and it will supply you what you need when you finally upgrade to a better video card.
All in all jacket with a new video card, good psu, and correct RAM you'll be good to go with this set-up for some time.
PSU link:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139005
*** I do have one very important question though: Did your tech tell you that the mobo and the rest is okay in spite of your old PSU's major fail? In other words, your mobo, etc. is good to go because it wasn't damaged by the psu failure, correct?