Yeah, you can.
PCI-e 2.0 has double the bandwidth of original PCI-e. So, new cards are ready to chew up that bandwidth. Even though most cards on market won't go through the bandwidth of the old PCI-e slot.
just watch out for ASROCK motherboards
some of their pci express slots don't allow the use of 2.0
post link and I will check it out for you
also check the list of supported video cards
The motherboard he has came in an HP Pavilion pc.
Here is the mobo specs.
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00496280&lc=en&dlc=en&cc=us&product=1815825
so is no good for a pcie 2.0 video card?
You can put a PCI-E 2.0 card into a non 2.0 PCI-E slot.
It just won't run to it's full potential.
Yes, it will work.