I currently have an iXtreme X2711:
Q6600 @ 2.4 Ghz
4GB of RAM (Upgraded from 2GB)
8500GT 256MB

I am planning on purchasing a Radeon HD5770 to upgrade my PC. I know that I will have to upgrade the PSU because the stock one sucks. But I have heard that PB standard PSU's are not the same as a standard PSU. So I am wondering will I have to purchase a new case and PSU and swap everything into that or can I get special PB PSU's?

I was thinking of getting this PSU either for my current case or a new case: OCZ StealthXStream 600w Silent SLI Ready ATX2 Power Supply
From the Novatech website.

Could someone please help me come to a decision?