Windows 7: Thinking on building a gaming server.

As the title says im thinking on building a gaming server with a few of my old PC components.
Im thinking of setting up a server for Counter strike source mainly.

My parts are as following:
Gigabyte GA-PH67-UD3, Socket-1155
Intel Core? i5 Quad Processor i5-2300
Antec Twelve Hundred Big Tower Sort
HIS Radeon HD 6950 2GB GDDR5 "TURBO"

And if im not mistaking i need a PSU ofc, some ram and a HDD.(any tips on what it should be, nothing to expensive)
Will this be powerful enough to run a gaming server?
And for what i understand i need a good internet connection aswel. I got a 25up/25down MB fiber connection.

any tips?