That'll work just fine for Minecraft as long as your Internet connection's upload speed is fast enough. I have a similar system with a Core i3-2120 processor, Windows Home Server 2011, and 16GB of RAM and it's flawless. However my Internet connection isn't good enough to handle many users.
It will be equipped with 8gb ram , also its Being bought for me as a gift, i plan to upgrade cpu in futureAdditional info : windows home server 2011 , dedicated 10mbs internet line, 8gb ram total. I will be happy if it comfortably holds 50 people.
Honestly, scrap the windows home server and throw a linux os onto it. If you're really trying to be conservative with your resources, that's a good place to start.
Also, if you're only looking to have 50-100 people, you can easily do this with 4-5 gigabytes of space, and if you have 10mbps of upload, which even though it is quite a bit, probably won't end up hosting over 40 people without lag.
So other than upload, like previously mentioned a cpu upgrade would do you nicely.
The internet is time warner high speed , not sure on the bandwidthBelieve it or not im currently able to host 20 people on an HP pavillion with 4gb ram, this is why im upgrading, the HP is dedicated but chunks after 20ish people