Sluggish Network Problem HELP!

[slightfoot]

Greetings all,
I am new here and was told that this was a good place to get networking questions answered.

I recently took over as Technology Director for the Toledo School For the Arts here in Toledo.

Our school runs a Local Ethernet network out to around 250 comptuers over 3 floors. Everything returns to the server room and connectes to three 3 COM, front port switches.

Here is where my problem lies, In an attempt to de-tangle the myriad of unlabled wires connecting the classroom runs to the switches with typical RJ45 / Cat 5 cables I think I may have severely injured my network efficiency.

In my zeal to organize the cables I began cutting them individually to length (most around 18 inches long) and happily labled them neatly with sharpies by room number and reconnected them. Then, shortly there after I began getting calls from around the building that the 'internet was down' and 'Why is the network so slow?'

I then began thinking that I heard somewhere that connections like this must not be shorter than 3ft or 1 meter in length in order to keep the signals from colliding.

Is this true? Do I need to have 3' of wire for each connection in my rack? Please let me know if this is the case, or what the alternative might be.

Thanks.