"..........we need to get a network card..."
Do you literally mean a network card like this? If so then I'd advise against that type of adapter for three reasons: 1) It involves opening up the PC. 2) Because the aerial(s) are at the back, the PC's case could obstruct the wireless signal and you'd end up with poor performance. 3) Nowadays, there's no advantage over the more popular USB adapters.
I'd recommend something like this wireless USB adapter. Roughly 70% of Amazon customers gave it five stars so it's likely to be a good performer. Another positive feature is that it can be positioned for the best wireless reception due to it being connected to a USB cable.