I first got TiVo in December 2000 and have tried using software on PC's and it just doesn't compare to the TiVo. The TiVo just works, I the only time I put into the TiVo is using it to watch TV. All the other software I've tried, I'm always having to fiddle with something to make it work every month. Think about how much you would be billing someone else for the work your doing with the software bases PVR's you will quickly be willing to pay $10 - $20 a month for something that just works. Hell, I currently own 5 TiVo's. 3 Philips series 1 units, 1 Series 2 DT and 1 Series 3 unit. I'm only using 1 of my series 1 units at this time. I might sell the other 2 or give them away for X-mas.


Now as for your questions:
The the HD's can be upgraded in all units. I've upgraded all of my series 1 units. The 1 currently in use has 2 120GB drives and a CacheCard. The others have 1 120GB drive and a TurboNet.

The series 1 units can have the custom network cards (TurboNet or CacheCard) added to them. The series 2 units have USB check TiVo's store for the adapter types. The series 2 DT and the Series 3 have 100MB ethernet port and USB for the Wireless adapter.

Only the series 3 unit can record digital cable by getting a cable card from your cable provider. If you don't want the series 3 unit at this time (Only really needed if you want HDTV) and you can't receive the stations you want without the cable cable box you can only record one channel at a time. The TiVo will be connected to the cable box and will use an IR cable to tell the box to change the channel. This can cause problems as sometimes the channel might not change. Some cable boxes have a serial port that the TiVo can use instead of the IR cable, most people say they have near perfect channel changes with the serial cable. If you decide you can do without the cable box I would recommend the series 2 DT unit as it can record two stations at once. Also the series 2 units support all the HMO features and TiVoToGo. One of HMO features lets you view recordings on other TiVos in your house. TivoToGo lets your extract shows to the PC and watch them on it or transfer the show to some portable devices.


Also please check out these forums

This is the hacking underground site: They have extraction / show conversion and other stuff.
http://www.dealdatabase.com/forum/

TiVo employees post here, but the site doesn't allow posts about non TiVoToGo extraction) / removing the DRM from TiVoToGo files. But it is one of the few sites I read daily.
http://www.tivocommunity.com/

I can would be glad to talk to you over the phone if you would like to know more.
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Chad