I have two PSU, the Antec NeoHE 500W and Thermaltake PurePower 600W.  
 
http://www.antec.com/us/productDet [...] odID=28500
and
http://www.newegg.com/Product/Prod [...] ower%2b600
 
Problem is I don't know which one would be better to use for my new system. It has:
Geforce 8800GT  
E6750  
2GB Ram
1x SATA Harddrive
 
And nothing else really worth mentioning.  
 
I have both the Antec 500W and Thermaltake 600W to choose to put in this system. I can't decide to go with the more reliable AntecHE or use Thermaltake for the extra 100W?
 
 
 

Either would work, both put 38 amps of power to the +12v rails, so the extra 100 watts is pretty much meaningless.
The Antec has the edge in efficiency and a longer warranty.

Go with the Antec, apart from what has already been stated, it is modular, which is nice for eliminating cable mess!