Is this PC suitable as a small server?

An AMD Athlon 2 x2 and 4gb ddr2 is installed.

Would like to install a small ssd in the PC and install Ubuntu on it as a server.

In order to have it as a small test / fun server nothing great small Minecraft server should run on it and a small website only for friends not a big traffic or something.

Do you think that would pack or would you advise me to a Raspberry Pi.

Of course it would be cheaper to take this PC because it is already available.

Wouldn't let him run 24/7 either.

In any case, more than a Raspberry pi is good but still poorly suited as a server 4GB Ram not really much and just an old processor

The part turns around at the lower limit of the requirements. The main memory is very tight, because this limits the number of players.

You can also read the Minecraft Wiki.

Should run, even with 4 GB. Have fun tinkering!

I would see if you can somehow get it on 8GB Ram. But I think Minecraft should be enough for a little hobby.

Such an SSD gets a lot out of it even for Minecraft servers.

The thing will be stronger than a Raspberry. A small web server will run wonderfully on it, no problem.

You can simply try out whether Minecraft is running on it.