And looking at http://www.geeks.com/products.asp?cat=SVR you see the used/refurb market to be plentiful with read servers to be had.
And all you wrote appears to be what a gamer may think of a server when servers are rarely overclocked and the real issue is the bandwidth.
Sorry but your post tells me you are new to servers. Try some cheap server but here's the biggest problem in your design -> Windows 7 Pro.
That OS has a connection limit so you would never get 25 connections. I bet you don't believe me so I'll end here with a note -> https://www.google.com/search?q=windows+7+pro+connection+limit
NOTE: That's usually HALF that as each user may get more than one connection.
So I have a pretty decent desktop right now that I built. I host multiple servers for multiple games such as minecraft, terraria, gary's mod, cubeworld, etc. on my computer as we speak. I'm going to college this year and I'm bringing my desktop with me. I doubt I will be allowed to port forward through my dorm's router, and I also doubt they'd let me set up my own internet and modem haha. Hosting directly from my desktop like I do will no longer be an option.
I've done some research and I was trying to decide how to go. I plan on having an SSD with 100GB+, 8 GB of DDR3 RAM, at least a 4 core cpu which I will overclock (probably Intel), not sure about the motherboard (are there any advantages to a server motherboard vs. a desktop motherboard?) or power yet. I plan to use Win 7 Home Premium since it is readily available to me, although I may end up snagging Win 7 Pro if it is very necessary. I also need a good way to reliably control the server remotely. I expect a max of about 25 people total connected to the various servers at once.
If anyone has any hardware/software suggestions, recommendations, or advice it would be much appreciated. Please do not suggest renting a server. Renting a server is not what I want to do and I am not considering it as an option. I'm trying to shoot for under $1000, and if that is too unreasonable, then a price range would be very helpful! Thanks in advance!