The best day trading software, hands down, is E-Trade Pro. Folks, it blows away Scottrade and even TDAmeritrade in my opinion. I've seen more people quit their day job and trade at home for a living using E-Trade Pro than any other software platform.
Day trading software alone is not going to automatically make you a great trader and allow you to quit your day job. You need to know a strategy for day trading as well.
Day trading is in someways, similar to swing trading but in other ways, it's totally different. When a trader tries to day trade full time and swing trade full time, it often doesn't work out because his attention is divided. So my advice to you is to try both and see which one you are better at, then totally focus on just that.