I made tests and reached more than 10K users with a Xeon bi processor and 4Gb of RAM.
I think a Xeon with a single processor and 2Gb should be enough for 5000 users but if you can afford larger like the bi-pro and 4Gb RAM, it could probably be safer.
in the text above, does this ‘10k users’ mean cocurrent or online, only a part of this 10k ‘cocurrent’?
or here, the definition of cocurrent is the same to online?