There are system reqs posted on their forums but I don't know if it's a sticky post (should be).  Because HS is programmed in flash, a 1.6ghz is a little on the low end of the scale.  It CAN do an ok job, but you need to disable the advance effects to make the experience more enjoyable.  Also, with 1.0, it doesn't run internally at 800 x 600 anymore, so its important to bring your desktop resolution down to maybe 1024 x 768 to improve the experience.  Try these and post if the experience is better, but again, a 1.6 is really starting to be ancient in the PC world.  I just upgraded from a 2.4ghz P4, and that dates back 7 years.  On my arcade cab, I have a 3.4ghz single core and the experience is pretty near seemless, except for a few of the advanced background effects.