I'm using PowerLogic Magnum 450W Pure - 900W Peak

Spec:

MSI PM8M-V Mobo
P4 3.2 HT Norhtwood
TT UFO Fan
CM Ice NB Cooler
Galaxy 6600GT AGP
Sound Blaster Live! EMU-10k1
1xsata 500GB Seagate - XP SP2
1xpata 80GB Seagate - Vista
1xpata 40GB Maxtor - Unix/Linux
1xpata Pioneer DVD-RAM
2x1GB Kingston DDR1
3x120mm (2 of them have LED) from my Shinobi Casing
Front panel LCD Display

I didn't OC anything

Should this be OK?

PC PNC (now Vantec) makes very high quality product which based on server/workstation quality standards. Their PSU delivers stable power output almost zero ripples. I'm not really keen to that type of model because it uses 80mm fan which makes it noisier than others. If u really like PC PNC then pick Silencer product line, more efficient and queiter.
Answer for your questions:
1) if your PC power consumption is 500W, it will draw much more because the PSU isnt 100% efficient. Let say your PSU has 80% eff, then it will suck the power from TNB around 625W.
2) Choosing UPS depends on total power consumption of your PC (Speaker+Monitor+CPU).



Slightly different because dependencies are based on PSU efficiency and hardware power consumption.