Xfx 9500gt VS sapphire 4550

both cards are low profile
the xfx 9500gt
and the sapphire 4550

the performance are of course, the xfx 9500gt is superior to the sapphire 4550 by an avg of 10fps of the benchmarks i saw

im doing an upgrade this weekend and still full of doubts if which card should i buy.
my choice is stuck between the two because of my 250w psu, and is wondering if which card is
safe. both cards passed on the psu calc.

*note: i cannot upgrade my PSU because it is OEM

here are the results:

4550

AND


9500gt

the 9500gt is almost on the 250w mark.
i will be playing at least 5hours or so, would i damage my psu if i run the cards at that load for that long?
both cards are priced the same so its a bit of a waste if im going with the sapphire 4550.
i dont mind playing at mediocre settings as long as i can play at high resolutions.

lastly, if i will be buying the sapphire 4550, would it be sufficient to play:
Need For Speed: Undercover, Burnout Paradise, GRID, Devil May Cry 4
even at medium or heck LOW settings as long as i play them at 1680x1050 or 1440x900 res

*My current system specs are:
AMD Athlon 64 x2 5000+ Brisbane 2.6GHz
2GB 667 RAM (1 stick)
160GB sata ii HD
Nvidia 8200 (my current gpu, its integrated thats why its sucky)
Windows Vista Basic