Pay a bit more for a switch and only buy known brands as budget ones are always based on old technology and generally don't work as well as more expensive makes.

I highly recommend ZyXEL switches. You can get the ZyXEL 5 port gigabit switch for £22 and it will perform much better than most others. It has some very nice features such as sensing the length of ethernet cables and adjusting its power for the length, and also altering power output to each port based on what is connected, or if the system on that port is on or off.

I always used yo buy Linksys switches but they really went down hill in recent years and now don't seem to make many consumer switches at all. Netgear also used to be good, but their recent switches have loads of issues with overheating. Something else good about the ZyXEL switches is their all metal casing.

Regarding ram. That is seriously old if it is similar to that link. I've not seen ISA ports since my old Pentium 2. Do you know what the maximum simm size is they support? 16, 32, 64 or 128MB? You might struggle to get the best firewall setup with a system that old, and FTP/NAS setup is out of the question as it would not support enough ram or CPU power.