Hello Franz,
Welcome to the Forum !
It's encouraging to note that you wish to acquire Ship Simulator Extremes. One of the primary concerns should be the suitability of your existing computer to run the Simulator smoothly.
I have taken a look at the Dxdiag you have posted and unfortunately it is not suitable due to two main components.
- the processor's clock speed of 2.2 Ghz is rather low as 3.0 Ghz is what is normally recommended.
- the graphics card is extremely low on memory. The one which SSE requires stands at a rank of 88 and your stands at 867
Your Windows Vista and the quantity of main RAM is suitable though.
I suppose HP will be able to tell you if you can upgrade the above two components or not. A word of caution here - you may have to replace the PSU (power supply unit) too, to support the graphics card recommended for SSE.
When you eventually do decide to buy SSE, I would strongly recommend that your first choice should be the DVD from www.shipsim.com OR the download version from the same website. There is another version through the Steam website but quite some users have had complaints. You may be able to buy the DVD from a store in the U.S. (physical or online) but in all probability you will have to use Steam to install it. Please check this carefully.
Please see attachment for the System Requirements of SSE.
That you mention you "enjoy the two previous games", I assume they are SS 2006 and SS 2008. Please register their License Keys in your Profile in this Forum and you will have access to all boards of the Forum. You can also get lots of free custom missions for SS 2008.
Regards
vin_sun