For a demo account for Sterling go here http://efficientexecutions.com/ExecutionSoftware/tabid/78/Default.aspx and leave them a message on their website saying you want a demo account, leave them your email address because they will email you the login info.
(Just a couple of comments). We obviously use the Redi platform (Goldman Sachs), and "back in the day" it could be a bit troublesome (pre 2001 or so). But since Goldman has placed so many people supporting it, redundant servers etc., the thing is really good. That being said, the various platforms have basically become a commodity...most work well, have similar features, execute orders quickly and all the rest. The major advances come from traders who have written programs to auto execute from the various platforms. Excel has a RediPlus addin, which makes it super simple for "non-programmers" to even adapt various programs for their specific needs. Even using FIX connections via Redi has gotten a lot easier, the support has been excellent the last few years. (Being "old school" - I still maintain that the "computer between your ears" is much more valuable than one on your desk, LOL). All the best, Don