HP Compaq dc7100 Ultra Slim Desktop PC

According to the specs found on page 2-3 of this tech reference, your system will only accept a single PCI card (no AGP and no PCI-E).

It doesn't matter which brand you choose (ATI or NVidia) as both will work, but looking at the limited choices of PCI graphic cards (on Newegg at least), and given your limited power supply (200 watts) it looks like your best bet would be the ATI HD 2400 Pro (PCI).

-Wolf sends