So I have been tinkering with my simple quite a bit.
I bought it originally as the DIY assembly kit back a while, long before the metal model.

So far I have:
Upgraded to the metal bed and extruder
Switched to braided fishing line directly on the shaft
Added a heater to the metal bed
Added a secondary fan to the extruder to keep it from overheating and melting the filament
Rebuilt the Y axis with Y-sag compensator off of thingiverse

Yesterday though I started having a peculiar problem. I noticed that despite the heated bed the print was curling.
I was wondering if maybe the problem was that the temperature of the bed was not reaching the print through the blue painters tape I use for adhesion.
I put a layer of painters tape between the thermistor for the bed and the bed itself, this solved that issue, however, now I have a new problem:

The hotend will not stay heated to temp if the heated bed, hotend fan, extruder fan, and hotend are all on simultaneously, to the extent that if left unattended the hotend actually cooled to the point that "cold extrusion prevention" kicked in.

I am assuming this is a power draw issue, and have considered buying a 500w power supply to replace the power adapter that comes with the simple, but I wanted to check in hear first and find out whether if I do hook up say.. a 500w ATX power supply.. do I risk frying the board having that much power draw? Will the same problem persist because of power management in the board?

Any ideas?

[reprap.org] etc. says it can handle it, given enough power.

The 500w of an ATX or other power supply is an upper limit of what it can provide, it does not mean that it will try to force the full 500w into board. If you hook up a beefier power supply, only 120W or 10 amps of current at 12V will go through the board's MOSFET and through the heatbed, with the rest of your electronics drawing their own watts out of the remaining capacity.

Based on [reprap.org] , a 500W ATX at 50% capacity should handle everything.

It is the amp output of the power supply not tbe watt input. What is you rated output on the 12volt side of the power supply?.
Anything less then 20 you may have an issue. Could also be the supply is failing, or any number of other problems. It would be better to look at all the parts that might be causing the issue, to find a failing part, rather then throwing money at a problem you don't know the cause.

Just my two cents..sorry pet pev of mine... I work with a group of guys that just thtow parts into a machine without a clue of the cause, and wasting a lot of money in the wake.

SOLVED!

Thanks everyone.

So, it turns out it was the power supply. The Printrbot Simple comes with a very low-wattage (230 I think?) power cable, because it doesn't have a heated bed stock.
I installed a 600w power supply from Fry's yesterday, and now all parts are running simultaneously. I was also able to hook up the non-controlled fan direct to the power supply so that isn't even running through the board anymore.

The prints are some of the best I have ever gotten out of this machine. No warping and very little Y-sag (compensator wasn't able to fix all of it, or needs to be tightened). Best of all, no jamming. I had constant jamming with the stock Printrbot Simple, and every print larger than a half inch would reliably be warped.