Dell latitude e5400 wireless card upgrade

Your laptop uses a mini-PCIe card, a half-height card, same as my laptop. As long as you get that format, it will fit. If there are drivers (and most should install automatically via Windows Update) it will work.

A couple of our forum experts use and recommend this model: https://www.amazon.ca/gp/product/B00MV3N7UO/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

Be careful when disconnecting and connecting the tiny antenna plugs that fit over the tiny posts on the card (kind of like snap fasteners on a coat). They are fragile. And be careful to note which sides the white and black cables connect to before you disconnect the existing card.

Whenever touching components or working inside a computer, wear a grounded wrist strap, also called anti-static wrist strap, ESD wrist strap, or ground bracelet. I know many people do such work without this, but it's a cheap and sensible precaution. Rest the laptop on an anti-static mat or at least a reasonable alternative such as corrugated cardboard.