3D CAD drawing

Hi all,

I haven't had much of a go at drawing up mechanical
designs on a pc (i mostly do electronics and schematics).

I was wondering if there's a cad package where you can
draw pieces separately, then move them on the screen
to assemble with other pieces, and rotate the assembly
to see it from other directions. Something that doesn't
cost thousands for hobby use would be good. I've used
turbocad a long time ago.