Need help regarding about PSU in my desktop [read description and 10pts]?

My PC is Acer Aspire AX3950 with PSU of 220w and it is a slim desktop. Can I upgrade the PSU to a maximum of 500w so that I can use graphic cards (now I am trying to use 5570)? If I can, could you name me or give me a link of the PSU? thanks.