Depends on how much you spend.
If you spent 70$ on that 700 watt power supply it's not surprising it's having difficulty keeping up.
I myself have a 750watt power supply that ws over 150$. When it comes to power supplies, the more you spend, usually the better they are.
I run a phenom 2.4ghz quad core, 4gigs DDr2, 2 8800GTX's in SLI and 2hdd's + an optical and 4 fans without issue. I was running 4 hard drives, but that was a while ago and since switched to a single 1tb hdd.
A true 700watt power supply should be enough to run almost any system that isn't running a true Tri-SLI or Tri-GPU gaming rig.
Edit, this isn't the exact power supply I bought, it was almost 5 years ago when I built my PC, but it's the same brand. I'd buy from them again.
720watt
Damn thing weighs almost 6lbs. That's always a good sign when a power supply is hefty.