^^ What they both said.
I guess I shouldn't have taken the thread so literal.
Lost Planet supports both DX9 and DX10, the difference being that if the game sees a DX10 capable card it will run with the extra features turned on. If the game doesn't it will run in DX9 mode. However, I take it that you can't seem to get the game to run on your X1600 regardless, so let's work from there.
The first thing to do is make sure that Vista is completely up to date as there are some critical patches to do with graphics that will help out in the performance department. Secondly, be sure to update your graphics drivers. However, you might want to try installing a lower set of drivers first, such as
Catalyst v.7.4. These were the first drivers that directly supported Lost Planet, so you might want to start with these, and work your way up to 7.6 or 7.7.
Also, since you graphics card is only one piece of the puzzle, you might want to check for updated sound drivers as well just to rule that out as a possible bottleneck/issue.