Ok, it depends on what you want. If you only want your basic cable stations (normally those below channel 100) then you can simply get the Slingbox tuner and connect it to any of your cable connections. It has a passthru connector so the cable would go thru the SB into the cable box.
If you want more than just basic then it becomes a little tougher. Do you have an extra set of AV connections from one of you cable boxes? If so then you can look at the Slingbox AV.
If you don't have an extra set of AV connections on the back of the cable box then you will need to step up the the Slingbox Pro. This has the ability to pass thru the AV connections. It also supports more than a single device. I have mine connected to my Tivo and am considering hooking it to a DVD Jukebox (400 dvd system).
If you don't have a network connection right at the cable box then you will need a power line ethernet adaptor. I went with the Slingbox version just to keep it simple but I know that netgear sells one as well.
Cost, this stuff adds up quickly.....
Slingbox Tuner $100 - $130
Slingbox AV $130
Slingbox Pro $200 - $225
Slingbox Turbo (1 or 4 port) $80 - $150
Slingbox Player for
Palm $30
For the AV and Pro you will also install an IR repeater so you can change channels on your cable box.
As you can see it adds up quickly... Remember that if you hook the AV or Pro to an existing cable box you take control of the device when you start the player on you phone or computer. Someone could watch at home, but if they or you change channels it will effect both parties.
One last thing... this will burn through your Treo battery as fast as possible. You are running the radio and display full time to watch. Think about buying a larger battery!
Bear