Having trouble connecting old computer to Internet

I have a really old computer which had been sitting around in my basement for quite some time, so today I decided to bring it back out and have it do something useful (ideally install pfsense on it). Just to give you an idea of how old it is, here are some of the specs, if you're interested:

CPU: Intel Pentium 4 dual core @3.0 GHz
RAM: 2 sticks of 512 MB DDR2 (1 GB in total)
Motherboard: Gigabyte GA 8N SLI PRO (LGA 775 socket)
Graphics Card: nVidia GeForce 6600 (256 MB VRAM)
OS: Windows XP

In order for me to do anything with this thing, I am going to have to establish an internet connection. But here is the problem: after connecting an ethernet cable (CAT 5e in case it matters) from my router to the computer, nothing happens. It's as if I never connected the cable in the first place. Around a decade ago, when the computer was purchased, it wasn't me who had set it up, so I am completely oblivious to as to what I have to do to get his thing to work. If someone could walk me through the process of doing so, or link me to a video or an online guide that would be really appreciated.

Thanks in advance!

Put Linux on it?

Will pfsense do?

Sure why not. I suggest it because you have XP right now... I just wouldn't even bother trying with XP. And youve nothing to lose, its an old computer.

Yeah the plan is to turn it into a router like Logan the Great suggested some time back.

Probably just a driver issue. I'd go ahead an install pfsense and not worry about getting XP working.

There is a possibility that the LAN port has gone bad. I have a few old boards that the ethernet ports are bad.