TJmax for the 2500K is 90C.
With the stock cooler, running all four cores at full load will hit TJmax within minutes, wherein the CPU will down-clock until the heat dissipates/core temp drops, which, in a few more minutes will never happen and it will be stuck running slower. If you have CPU-intensive apps, keep a temperature logging program running to see if its enough.
I max at 66C @ 4.2GHz with the Zalman 9900 and it looks spiffy,
http://www.zalman.com/ENG/product/Product_Read.asp?idx=416Just about any aftermarket HSF is better than stock.
Your GPU temps are fine (what GPU anyway?); my Gigabyte GTX580@850MHz stays in the lower 70's at full load (Skyrim as of late); the three fans on it with the case cooling helps that.