: I have an old Craftsman table saw with the really nice, heavy cast iron
: table.

: Do you think it would be worth having the top machined so the miter gauge
: slots are "inverted-T" shaped, rather than rectangular, so I can
: use them to hold down jigs, feather boards, etc.

: Or should I just invest in a new saw...Delta Contractor's saw, maybe?

Somebody posted a link to this homemade featherboard rig a while ago. I haven't tried it yet, cuz on my lightweight Craftsman saw the miter-slot is too close to the blade to be useful for ripping strips (at least it is in the setup I prefer). I may make a couple anyway for other jobs. They'd be useful on the router table too. Since you're the king of home-made "stuff", this would only be about 15 minutes work for you?

With that cast iron table of yours, those magnetic hold-downs could work well. My table is aluminum, so that one doesn't work too well work for me.