I actually have a GEFORCE GTS 450 in my old computer.
Would you recommend that?
Yes the 450 will be better then the 530 for a DX9 game like skyrim
It's really the 2 last numbers that show what tier your video card is. Only when a new generation comes up it kinda gets whacky
So a 480 is better then a 560
a 450 is better then a 530
But a 580 is better then a 480
And a 570 is probably really close to a 480.
So a new generation above is better... but doesn't mean no matter what it's better.
As for you i7 2600, you have one of the BEST cpu's available. It is JUST your videocard holding you back. Even your 450 won't "max" but it will be loads better then the 530 if i know my math right. Although I don't really look into anything less then #60 series for nvidia (460-480 and 560-590)
personally 570 and 580's are over rated. By the time a game comes out that needs them, the 600 series will be out.