Update:
So, I just switched the PSU to a low-quality Ultra 400W PSU that I have on-hand, and my PC started to go into its POST routine!
I'm going to put it back together with this PSU and see if it works once everything is reconnected and back in the case. If it does, I'll happily buy a new PSU. I think the Enermax is still under warranty, so maybe I won't even be out any money.
Wish me luck...
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2.4 GHz AMD Athlon 64 3700+ Clawhammer - 2.0 GB DDR RAM - Thermaltake Toughpower 650W PSU
NVidia GeForce 7600GS 512 MB AGP 8x - Sound Blaster Audigy 2 ZS Platinum Pro
1x250 GB SATA - 1x120 GB SATA - 1x120 GB IDE