cude to grid
 

how do i make a cube so it goes straight with the grid?
i forgot to say plz

you can snap along the grid..
select your cube and hit "w" to go to move.. then hold "x" down and click on the circle of the move axis.. now move the cube.. :p

or the super fast snapping method....
select move, hold down ur snap tool (x in this case for grid snap) move ur mouse over a grid point, hold the middle mouse button and give the mouse a lil jerk, instant snap :)

what grid line space do u use
i have it on 5 at the moment
i cant line a cube inline with the lines