fast, max fps, opengl on, custom colors/mobs/sky/etc everything non essential off, normal render. i loaded up and flew around in creative at full speed, chunk loading was nice, average fps's were as stated. how much that would change with an advanced base? not sure... I'd load up bevo's SSP on bevo's tech pack but it barely runs on my current machine heh. animations were left on, so i imagine unless you build a glass base inside a lava pool it would be decent. if you play SMP you'll probably see better performance, since you wouldn't be running a "server" locally.
#realtalk, though. if you have any dreams of mass automation, many chunks being loaded with quarries running, etc. drop them. the pc will barely handle you running around, building machines, running them, and mining yourself.
good luck.