Let the hive mind of Engadget get that for you.
"I own an iPhone 3G and I'm looking for a decent speaker / alarm clock for it. I am going to listen music in a mid-sized room, so I want nice quality speakers with solid bass. I also want to use it as an alarm clock, so it would be great if there is such a feature. The price can be low-mid to mid-high range. I was looking at the Klipsch iGroove SXT; it's powerful, slick and the reviews are good, but it doesn't have an alarm clock feature. It's no deal breaker if I can set it up from the iPhone, but I'm not sure. Thanks!"
The x40 series features their HD traffic which yours doesn't and won't have. The HD traffic uses anonymous cell phone data from Vodafone. It tracks the speed of moving cars on the main primary and secondary roads. It combines this with government data and RDS-TMC data and then is verified by TomTom manually before being sent to you - every 3 minutes. Use this in conjunction with IQRoutes which you also don't have, the x40 will know the fastest routes at every 5 minutes of the day.
That's pretty advanced stuff. When I used the IQRoutes, I managed to save a good 10 minutes off my travel time. My old satnav didn't tell me about that route, nor did google maps. It seemed longer, yet it was 10mins faster.
So there is a lot to look forward to for the TomTom x40 series, I just wish they would hurry up the release :-S