Cheaper to Upgrade or buy new pc

[charlie476476]

My biggest concerns is if i did replace the video and add 4 gigs of ram. I feel the processor couldnt handle it. I would guess the last thing if all that didnt work would be to replace the mothrboard/cpu with perhaps a AMD Phenom™ II 955 Black. Also with the memory being 667mhz how does that compare to 1066 and 1133? From what I read its almost no difference? Just wondering if I get a new cpu/motherboard. If those 2 sticks of ram will work along with adding 2 or if i need for new sticks. Thanks again I have limited knowledge on pc tech so all advice helps

Do you think $500 would be enough to upgrade this pc without having any issues in Cat running 5? or better start shopping for a new gaming pc

thanks