I've heard that if you use two 25 feet Cat5 cables connected with a connector it will run MUCH SLOWER than using one 50 feet Cat5 cable...is this true? i doubt it, but i just want to make sure

It depends, what kind of connector are you talking about? If you're using a hub or something like that to connect the segments then yes, otherwise it shouldn't effect your speed much at all.

Enterprise organizations typically run servers with multiple NICs installed. You have to have the appropriate hardware to handle it though. These businesses typically have switching equipment which is capable of tying together two bandwidth streams such as in cases like these.

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I doubt you will see much of a difference if you connect 2 cables together. Unless the connector or adapter you use does not allow for a good connection. Obviously having one 50 ft cable is better then two 25 foot cables combined.