Dean - as you've got the silverfast software bundled, you've nothing to loose apart from a little of your time to try it. It's definitely a better scanning solution to the ScanGear software, some people get on with it, others don't - but i'd definitely give it a try before spending any extra money. It's not by any stretch of the imagination a user friendly program, and the instructions would probably make more sense if read in the original german, but it IS capable of some decent results if you put the time into learning how it works.
I have to say however, that their upgrade policy has seriously hacked me off, and if/when I decided to upgrade, I doubt I'll be sticking with Silverfast, and will probably end up going with VueScan, if nothing else, because they do at least seem concerned about their existing user base.