I Need a New Video Card

[Securb]

I put in the video card and the computer froze, crashed and wont reboot. I am not putting another cent into the POS. I am starting over new.

HP Pavilion p6670t customizable Desktop PC
Genuine Windows 7 Home Premium 64-bit
Intel® Core™ i3-540 dual-core processor [3.06GHz, 512KB L2 + 4MB shared L3 cache, DMI 2.5GT/s]
6GB DDR3-1333MHz SDRAM [3 DIMMs]
750GB 7200 rpm SATA 3Gb/s hard drive from 500GB
512MB DDR3 ATI Radeon HD 5450 [DVI, HDMI, VGA adapter]
LightScribe 16X max. DVD+/-R/RW SuperMulti drive
16x max. DVD ROM (player)
Integrated Ethernet port, No wireless LAN
15-in-1 memory card reader, 2 USB, audio