Some PCI-e 1.0a (2003-2005) motherboards have compatibility problems with newer cards. But there haven't been outright incompatibilities like that since PCI-e 1.1 was introduced.
I have to question that recommendation for a CoolerMaster power supply. CoolerMaster has put out really, really awful power supplies in the past. They've gotten better, but that GX-Lite 500W you linked is a discontinued power supply shaped fire hazard slapped together by ATNG. Enhance-made CoolerMasters (most of the CM Silent Pro line) are quite a bit better.
Seasonic (and Antec and Corsair, which resell Seasonic under their own labels) dominate the quality power supply market at lower wattages and popular prices. Any Seasonic (especially S12II, M12II), most Corsair (though they've been changing their manufacturers for the worse), and some Antec (especially HCG, Neo Eco, and True Power New) are good quality.
If you want to find out who really makes power supplies, Tom's Hardware publishes a comprehensive and regularly updated list: http://www.tomshardware.com/reviews/power-supply-oem-manufacturer,2913.html