Serious issues with ENNvidia 8500GT silent and ati readeon 4350 HD

[mRt0x1c]

Hello toms hardware i need help about my Nvidia 8500GT it has weird things happening.First its overheting to 80C (lol that should be cold for that card but k) and after playing wow with 127 fps for 2 minutes(settings and res are at mininum) my game froze and the card temp was 81C.And i need to ask since i got my ATI READEON HD 4350 silent for 5 dollars(won on auction tested and works) i will put it and replace the nvidia 8500GT but will i have the same problems again i need to ask that and pls dont suggest new pc parts cause i dont have money for a new pc right now and the parts in my coutry are like 20$ more expensive that in the USA.
My other pc specs are:
Intel Celeron D 351 3.20 GHZ
Deepcool Cpu fan ck-77509
1 gb ram ddr2
motherboard is Biostar I945C-M7B
OS is Windows xp sp2 pro
For nvidia im using 169 drivers cause all other drivers cause the card to freze at startup or get bluescreen after 3 minutes of play
And i disabled the integrated intel gma 950 in bios and xp and i set the pci-e as first boot option and its enabled help pls

 

[mRt0x1c]

forgot to mention it happens in all games i have problem while playing League of LEgends fps goes from 40 to 5 after 10 minutes of play do to overheat i think so a soultion would be helpful