A bit brief on the specific MOBO model you have. As there seem to be a few of those Motherboards, under the ASrock Dual Vista name(as below). However one thing they have in common is 1x PCI-E slot for the graphics card. So looks like thats ok, you should know anyway by sight, having added removed the GPU a few times that you have this [URL="http://images.ncix.com/forumimages/CCCFEEA9-174B-810A-D4139D271BF34928.jpg"]PCI-E x 16 slot[/URL] or not.
Although i havent heard of this brand of PSU. 450w is way more than enough for a 5670 GPU as they are one of the least power hungry DX11 cards about, and on the plus side these GPU's dont need any power connectors from a PSU either, its uninstall your old GPU + drivers, then just insert, screw in, update drivers & off you go.
I havent even heard of that ATI GPU you listed, which you had before, but i am guessing an ATI 5670 is gonna blow that away. And you could even add another 2GB of RAM if your Motherboard supports it, that will speed things up for you too.
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Zowie AM-GS/Filco Maj.2 (mx brown)/Senn.PC360/Corsair SP2500
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