I don't think there is any one answer for finding the right trading system as I think it really depends on your trading style. Most people should be pretty familiar with my style which is short selling and I tend to hold things for a few minutes to a few days with a few hours to a day being average. I have 2 computers, a 500mhz which I use for doing up charts and scanning the boards, and a 933mhz for level II and my broker. 1 monitor for each (a 15 inch and a 17 inch), although I plan on getting another for the 933. I use E*Trade as my online broker through which I get free level II and free DSL service due to the number of trades I make. I have a backup ISP just through a 56k modem, and have a Sprint PCS wireless phone with wireless web access in case I need to call my broker or check quotes or make trades when I am out. I also have a TV tuned to CNBC. I don't subscribe to any other services or special software and I am pretty efficient with this modest set-up as it works well for me.
This should give an idea of what I use anyway.