Power Requirements to Mill HSLA & Mild Steels

I am planning to purchase a CNC Mill or Mill and CNC Kit in the next
month. I would like to know what size of motors I would need to mill
High Strength Low Alloy (HSLA) and Mild Steels. This is for hobby
work so removing a ton of material quickly is not necessary, but then
again, I don't want to be taking really small cuts just to prevent
problems.

Also, any advice whether to buy a complete CNC Mill or a manual mill
and add a CNC kit to it? Any suggestions about CNC kits...which ones
are good or not? I need to stay on the smaller-size of mills...mini-
mill-sized or a step larger.

Thanks,

David S.