I have an old gigabyte GA-P35C-DS3R motherboard. On it there is also written "FSB1333 Multi Core CPU...". I want to install a wireless card, but I am not sure on what models are compatible because I don't think this motherboard has a PCI-E slot (athough one of the slots says "PCI Express", the slot is still "long" like regular PCI, I really am a noob). For example, is the Tp-link TL-WN881ND compatible or not? What about the TP-Link TL-WN851ND, which looks more like it could fit in the slot pins? Also, once the card is installed, I will not need any cable right? My motherboard looks like this: https://goo.gl/images/f7fzNe Thank you!
It has PCI-E, and PCI-E is backward compatible, so you can put a PCI-E 16x or 8x card in a lesser speed slot and it will just give a modest impact to performance.
If you don't have faster than a 480Mbps (megabits, not megabytes) internet connection, I'd just go with a USB 2.0 Wireless adapter. Wireless cards are cheap tech, USB is easier to replace if there is ever a problem, and a USB device will usually have a better antennae to give you a more reliable connection. It also lets you do things like disconnect from the internet manually or plug it into other devices later on.