New video card problem no display

I recently bought a new computer:
HP Pavilion p6530f
Operating system
Genuine Windows 7 Home Premium 64-bit
Processor
Intel Core i3-540 Processor
Memory
6GB
Memory speed
PC3-10600 DDR3 SDRAM memory (3x2048MB)
Total memory slots
4 DIMM (240-pin, DDR3) (one available)
Maximum memory expansion
16GB
Graphics card
Intel HD Graphics
TV & entertainment experience
N/A
PCI expansion
1 PCI Express x16 (available) 3 PCI Express x1 (three available) 1 MiniCard (available)
Hard drive
1 Terabyte Serial ATA hard drive

And if I bought a new video card I could play all the new games with at least decent settings. I bought the, "Galaxy Gefore Gts 250 1gb, 256bit, DDr3. I installed it and the fan on the video card turns on, but I can't get a display to come up. Would that happen if my power supply wasn't big enough? Or am I installing it wrong?
 
The computer is using onboard Intel HD graphics so that needs to be disabled in the BIOS before the new card is inserted in the expansion slot. Make sure to uninstall the old drivers as well or it could cause problems when the card is installed.
 
Well after looking through the bios I didn't see the option, so I disabled it with the device manager. I still didn't get a display. I think my power supply is only 250w and my video card needs 250w all to itself. When I plugged it in and left it running, my computer ran very slow. Would the lack of a decent power supply = no display?
 
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