Changing the graphics card on a dell inspiration 545?

I'm pretty sure the graphics on this system are integrated so you can pretty much slot in any new graphics card you want, the motherboard carries PCIe x16(1), PCIe x 1(1), slots, all you have to do is buy a suitable W7 compatible grphics card, open the case up slot it into the PCIe x 16 slot, put the side back on boot up press F2 or DEL to enter the BIOS, turn off the integrated graphics in the BIOS, save and exit, boot up windows which should find the new card, if it asks to install drivers cancel and use the manufactureres disk that came with the card to instal the relevant drivers and software.