TS - get a branded 500 watt psu, yes a 500 wat is enough with a 30amps or up on the 12v rail. even better if you get the silverstone st50f-es 500watt with its single 34A 12v rail.
Dont get the gtx 460, the card has been phased out already, chances are lisod kaayo na e pa rma if defective since wala na gyuy stocks ana.
A gts 450 is good enough on mid setting games at 1600x900 res or lower. If you plan on playing on 1900x1080 res get the 560 non ti card (yes theres a non ti version of the 560 recently released to cover for the 460 on the midend range), its the replacement model for the phased out 460 and has exactly the same specs with higher clock settings and cost around 8-9k get this one instead if you like.