Easiest way to block a port
 

I need port 7520 blocked.

What I do.

Turn off your computer.

Can someone tell me why port 7520 is the worst port ever.

Get a firewall.

Yes.
...and if you're "seriously concerned" about blocking that port, a hardware firewall is the way to go.

He's right. Get a router (do not step outside your DMZ) so you can port foward the ports you want. Makes life sooo much easier!

Do get a firewall, but be aware that just having one isn't enough. Most firewalls are configured by default to allow no inbound traffic but all outbound traffic. So if you're trying to block an activation or serial check, or stop spyware from phoning home, you need to take the extra step to block OUTBOUND traffic across the desired port as well.

Different firewalls have different ways of handling this, but it's usually under a "Firewall" or "Rules" panel. Check the manual for the specifics on whatever model you acquire.

My personal recommendation is a Netgear ProSafe. It'll run you some extra coin, but it's a damn nice firewall with some powerful advanced features that consumer D-Link/Linksys/Microsoft routers don't usually have.

As CelticWhisper suggests, get the Netgear ProSafe firewall.

One question though, why block port 7520? or is there something about the port that makes it especially evil?