Best Graphics Card for my PC Help

[HP_a6640d]

Hi there, i was wondering if this cards will not fry my computer,

this is my pc specs
Originally, HP Pavillion a6640d ( i realize buy prebuilt pcs crap)

https://h10025.www1.hp.com/ewfrf/wc/document?docname=c01537815&tmp_track_link=ot_faqs/top_issues/en_us/c01537815/loc:2&lc=en&dlc=en&cc=us&product=3794118

2+ years and still counting

Specs

samsung 320GB hdd
15in1 front card reader
2gb ddr2 ram(1 stick)
sony optiarc DVD-rw
conexant 56K modem ( i take it out coz im not using it)
and psu Bestec 250w

the bestecs psu specs

+12v / 14A -12v/0.8A
+5v / 25A +5vSB 2.5A peak
+3.3v/18A

+5v & +3.3v 165W max
+5V & +12V 218W max

whats the best graphic card can you recommend?

im leaning to
Sapphire HD 5570 1GB HDMI, and Sapphire HD 5450.

whats the best card i can buy? without sacrificing the Whole computer.

btw im running its 20" monitor (1680x1050)

and playing with the intregrated around 800x600 at lowest settings ( duh.. )

 

[Mata51]

Sapphire HD 5570 1GB HDM is a good card but you will need a new psu because it needs 400w+ to run at its best

 

[jamieb123]

Yeah ^^, I think whatever you get It would be worth it to get a new psu