Hardware Requirements

I was wondering what the hardware requirements would be for a LAN dedicated server capable of supporting 24 people?

I would use a 3.0GHz P4 (with hyper threading) if you had one.
People have said they can run a 24 man server with as low as maybe 2.4GHz.

As for RAM, make sure you have at least a gig for windows XP or server 2k3.

If you really must have Vista on the server box, make sure you have at least 3 gigs of RAM, maybe 4.

So I don't need like a crazy quad core overclocked, with 8Gb of ram and 4870X2 then? Most modern computers could handle it?

You don't need a graphics card.
1 or 2 gigs of RAM should work fine.
SRCDS only uses one core anyways, you you don't need dual/quad core unless you are running more then one server on the box.

As long as you have over ~2.4GHz on the core you should be fine.

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How does this look? CPU Overclock to 2.5ish
Will the server run in a command line type interface?

There's no way in hell you can run a a server on that CPU.
I'm being told you should spend about 50 bucks for an athlon XP.

Do you plan on running this server from your home connection?  If so, what's your bandwidth?

I think that would work. I have a internet dedicated server that runs 16 people fine and its a pentium 3 1.3 ghz with 512 mb ram... Albeit I don't run humongous maps on it.

If you want to spend 50 bucks then you should get the celeron DC: http://www.newegg.com/Product/Product.aspx?Item=N82E16819116064

Its the best cheap dual core processor out their.

brianfast, you do NOT want to run a SRCDS on a Celeron processor.  That's why he shouldn't use the Sempron, which is like a Celeron.

http://www.newegg.com/Product/Product.aspx?Item=N82E16819103199
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How's this one? again, an overclock to 2.6/2.8ish. I would drop the 2gb of ram to a single GB, for cost effectiveness.
Is windows preferred to a linux distro?

For a single server?  Sure.
However, It's recomended that you don't OC a server.  But that's a personal choice.