Not the fastest combo on planet Earth but certainly the cheapest around. It will be a good stepping stone for a basic system capable of dealing with Vista. Please consider that it is first and foremost an ENTRY system. If you can find a better or cheaper Dual Core combo at this price, then please do post it for the sake of everyone.
MSI K9MM-V Socket AM2 onboard VGA 6 Channel Audio mATX motherboardhttp://www.ebuyer.com/product/122761
AMD Athlon 64 X2 3600+ Socket AM2 (1.9GHz) 1MB L2 Cache OEM Processorhttp://www.ebuyer.com/product/136311
OCZ 2GB DDR2 667MHz/PC2-5300 5-5-5-15 240 Pin DIMM Value Modulehttp://www.ebuyer.com/product/142340
Note that you will need a fan for the CPU and you may use your existing fan if possible.