I have the ATI AIW 9800 PRO...it's a TV tuner card and a top of the line video card for gaming. It was expensive, like 325 bucks. But if you're not into gaming and you just want a TIVO, you can get away with the ATI AIW 9700 or 9600. The 9700 is 200 bucks and the 9600 is 162.
www.newegg.com is a good site to get these videocards.
As for the refurbished dell monitor what better place to get this than dell...currently it's 800 with 10% off so 720+shipping. Here is the link to the dell refurbised store
http://www1.us.dell.com/content/prod...l=en&s=dfh
Good luck. One last thing, you'll need a monster HD because the TV files can get pretty big, something like 1.5 GB per hour of tv. I have a 200GB drive and about 100 of it is dedicated to TV files.
My bro actually has the Dell 17" TV/monitor it's basically a smaller version of the one you want. He love the thing and says the TV picture is great. He uses it as his primary TV for his dormroom. The only thing that sucks is that the max resolution is 1280x768. For the 23" I think it's the same. Generally you need 1600x1200 to multitable without overlap, also for spreadsheets, games, you sometimes want to run 1600x1200. I have to say though 23" is huge and it would be cool. Also just note that it's an LCD TV/monitor not a Plasma.