Upgrade the CPU?

I have a home made desk top PC. The MB is a GA-MA74GM-S2 from Gigabyte, CPU is an AMD Phenom 955, 2.2 Ghz quad core, 2 x 2 sticks of 800 Mhz RAM, video card is a Evga Nvidia 9600 GSU w 1 gig of RAM, and an ANTEC 450 watt PS. I have been told on the graphics forum that I can upgrade my CPU to a AMD Phenom II X4 955 Black Edition Deneb 3.2GHz 4 x 512KB L2 Cache 6MB L3 Cache Socket AM3 125W. But the Gigabyte web site says the following: "If you install AMD AM3/AM2+ CPU on AM2 motherboard, the system bus speed will downgrade from HT3.0(5200MHz) to HT1.0(2000 MT/s) spec; however, the frequency of AM3/AM2+ CPU will not be impacted. Please refer "CPU Support List" for more information. ". Can someone explain what the heck this means? I want the higher speed CPU in order to make a better graphics card feasible. Also, will I have to install a higher wattage PS? And will my present MB support the 125 watt CPU? Thanks in advance

It means that the bandwidth (in practical terms) that the Phenom II 955 can manage will be reduced because of a different technology (HT3.0 -> HT2.0) on your motherboard, however the computational power itself that the processor has, won't be impacted.

Example: moving things around in memory won't be improved, but making calculations on the CPU will by a lot. Games could be both, since there are games which are CPU bound (core and speed) and some are more bandwith bound (use a lot of memory: Crysis).

Cheers!

EDIT: I'm sure having the PhII 955 is an upgrade that can manage a "bigger" video card. Now, some "value" oriented MoBos don't support 125W CPUs, might want to check the list and see if there's more than the standard 95W CPU support.