Program and BIOS Temp Difference

The Soyo Hardware monitor program that came with my Motherboard reads my CPU temperature to be 75C. I can do a quick shutdown and get into my BIOS and read a temp of 45C. I experience NO stability problems. I am just kinda curious about this. Any thoughts?

P4 3.0GHZ 800FSB
The proscesor was clocked at 2.99GHZ using windows, I just bumped the FSB by a couple to get over the 3GHZ mark (Mental symbolic thing)

Soyo Dragon 2 Platinum (Complain as you might about soyo, but can you run 12 HD's without any expansion cards?)

1GB PC3200 Black Diamond (Is that a real manufactuerer? or just a name?)

Stock Pentium Heatsink (Going to put on my ThermalTake Volcano 7+, but lost the clips [was on AMD] any ideas for where to get them?)

Crappy 350W PSU (http://www.buyxtremegear.com/ps102110.html , is that PSU bad? My case is clear and UV reactive, wanna keep up the gig)

ATI Radeon 9500 Pro (Cant overclock the darn thing without some modification <shrugs> )

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