well ive already got 2 PSU's setup (300w mounted ontop of the case)  

The 450 watt powers the CPU(and fan), and motherboard, while the 300w powers the harddrives, DVD drive, and all the case fans.

But the 450 watt still heats up quite a bit while gaming. the exaust port is still very warm to the touch, while the 300w psu is still very cool, its not generating any heat at all..

now for the big question :p lol
Is it possible to run 2 or more power supply units in a parrelell setup, like one would do with batteries? (not increasing voltage, Just increasing amperage?)

deffinatly dont wanna increase voltage lol that could be bad..  

but can I just connect all the wires from both supplies together, then plug it into the motherboard? or would it be more complex then that?

Lol im way too poor, and stubborn to purchace a new 700w PSU when thers unused ones just laying around the house to tinker with  
Thanks guys!