i want to buy new VGA card for playing game like skyrim (all video option set mid-high) so what vga card better for me if my pc spec is :
windows xp 32bit
processor dual core 4.3GHz
I don't think any good graphics card will run that well on a 450w psu especially with skyrim at mid to high settings. Im probably not the best person to take advise from but i would probably save up for a new power supply with a minimum wattage of 550 that is made buy a trusted manufacture such as Corsair, Antec or Enermax and i would probably buy an hd7770 or maybe even an hd6870.
HD 6850 and GTX 560 (non ti) will be a good choice.. Your psu will handle those cards if it is made by a trusted manufacture.. Post your exact psu model and details about it.. Such as how many amps on +12v rail.. That is the most important thing.. Not the watt.. both cards requires 25A on +12v rail and minimum 450W psu..