I have an HP Slimline s5710f BV627AA
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c02627981&cc=us&dlc=en&lc=en#N101
The documentation notes that it has 2 PCIe X1 slots with one that is accessible.
I bought a Intel Wireless-N 7260 - Network adapter - PCI Express Half Mini Card
Intel...