Yeah what DJ professor said...
You can use any modeling program...
And as for High-poly or low-poly....
High-Poly is mostly for Rendering use only...
And for rendering a Normal-Map out of it.
Look at Jon's and Bond1's thread about the x10 models etc..
They exlained to you, that not everything has to be a somewhat
Higher-Poly model for just looking good...
Your most concern is the Texture, and since FPSC x10 also uses
a better Normal-Map and stuff..
Therefore the Texture, Normal-Map. are the biggest concern..
The better the Normal-Map, the higher the polycount will look like.
But for polycounts, i think that with x10 it doesnt hurt to stick with:
2000-3000.
Since it can easily handle more than the current version.
Hope it helped!
Cheers,
Cheese Cake.