Mousemonkey :
I wasn't having a pop mate it's just that I see a lot of people put Palit in the 'Not so good' category and the ones that I know of seem OK so I thought I'd try a couple.
That's why I never bothered with Palit, early reviews would mention them having low reliability with overheating, breaking down, and terrible support. Within 2 years ago I've heard mainly good things, one being that they can keep their reference designs cooler than normal without sacrificing with downclocks.
A 5670 would be reasonable with your build, a 5770/450 may cause issues with your PSU. That, or upgrade to a 500w PSU and then get a 5770/550.