well, you will find three types of cables in market
1]Cat5
The normal network cable, cheap but not the best. Avoid this one. They become hard in a year or two time and then the internal wire can break even on at 270 degree turn. Sells for 12/mtr.
2]STP Cat 5 (Cat5e)
This is the high quality Cat 5 cable with shielding given. They sells for 24/mtr. Cat5 and Cat5e are used for 100mbps network. for a gigabyte network, use cat 6, since they have a higher bandwidth. SNR in cat5 sux a lot.
3]Cat 6
For a long term usage and reliability, nuthin beats cat 6. but since copper prices have risen, they are selling for around 30 Rs/Mtr. Also, they have a thick plastic wire running between the 8 wires, which prevents it to break at sharp turns. ask any network admin, they will say, that its difficult to setup a cat 6 network, since they are very difficult to bend and crimp.
We have just setup a gigabyte lan within a small section in office, and we are witnessing a speed of 45MBps+. This is also due to HDD speed limitation. This was possible with cat6 and giga-switch.
I did enquire about STP Cat6, as theoritically, they are suppose to be the best with lowest errors. But they are not avialable anywhere..