I would wait for the 6xxx series ATI cards, may not be available till next year though. So I assume the problems you have with your GTX295 are no dx11/heat/power/dual GPU game support issues? It is still a powerful card by todays standards, a 5870 will be faster on some games but not all. a gtx480 would be a worthwhile upgrade but is a power hungry card, if that is a concearn of yours.
My exact problems.
Power isn't a problem, I have a 1250w stable PSU. I guess I can hold off until the 6xxx series. What's Nvidia's new lineup?